EPSON Perfection 4870 PHOTO Scanner Review: There Is No Limit to Perfection!

This January in the gold-miners’ city of San Francisco EPSON Corporation unveiled its new scanner of the Perfection family, intended as the new flagship product of the series. The manufacturer targets the Perfection 4870 at "advanced" amateur photographers as well as at professionals. So let’s find out why this solution is so remarkable.

by Sergey Samarin
05/25/2004 | 12:17 PM

The market of SOHO scanners (Small Office Home Office) has always been a place of violence. The manufacturing firms are all fighting each other for one reward – the potential customer’s money. For your purse and mine, too. This behind-the-curtains vehement fighting sometimes proves too much even for world-renowned companies – you can recall the fate of AGFA that had to leave this lucrative market. The highest competition gives only two ways of behavior for the manufacturing companies who want to stay alive.

 

The first way is offering the produce at customer-appealing prices; the second way is improving the hardware stuffing and the software coating, updating the model range regularly. These two ways are not perfect, though. You can’t reduce the price forever – you’ll surely reach the level of the manufacturing cost of the product. And however hard you improve on a bicycle, for example, you always get the same bicycle, but only an improved one. Anyway, prices are going down and new technologies are being implemented – there’s no end to this war!

Of course, for a SOHO scanner to acquire an innovative technology, this technology should be ported from a model that belongs to the professional sector. In January 2003 we welcomed the miraculous scanner EPSON Perfection 3200, which alone won more valuable prizes from the industry authorities than a pack of pedigree bulldogs. I confess that a thought crept into my mind then, “There just can’t be anything cooler than that! That’s the height!” And right at the moment when I was thinking this very thought, the secret labs of EPSON ware already developing their new, perfected weapon to replace the blameless Perfection 3200. So there’s no end to perfection and EPSON has surprised us once again? In this article I’m going to answer this question and expose the secrets of newest optical scanning technologies, while at the same time reviewing the EPSON Perfection 4870 scanner!

Please Meet EPSON Perfection 4870 PHOTO


EPSON Perfection 4870 PHOTO – at your service!

This January in the gold-miners’ city of San Francisco EPSON Corporation unveiled its new scanner of the Perfection family, intended as the new flagship product of the series. The manufacturer targets the Perfection 4870 at “advanced” amateur photographers as well as at professionals because the scanner features the capability of digitizing transparent originals of all formats, some of which had been only available on narrowly-specialized slide-scanners. While such machines are not much relevant for a home user due to their high price, the Perfection 4870 offers itself for very modest money. Its qualities are comparable to high-end slide-scanners, but I doubt there are its likes as concerns scanning sheet originals.

The new scanner comes in two versions – PHOTO and PRO – which mainly differ in the bundled software. This is the reason for the PRO version to be positioned for the Western market where bonus software is always welcome.

Before proceeding further, let’s have a look at the following table which lists the declared technical characteristics of the EPSON Perfection 4870 PHOTO:

Technical Characteristics

Manufacturer

EPSON

Model

Perfection 4870 PHOTO

Scanner type

Flatbed single-pass color image scanner

Light source

White cold cathode fluorescent lamp

Converter type

Alternative six-line color CCD-matrix with on-chip microlens.
122,400 pixels (20400 x 2 lines x 3 colors)

Max. optical resolution

4800dpi

Mechanical resolution

9600dpi (Micro Step Drive technology)

Interpolated resolution

12800dpi

Max. color depth

48bit (48/48)

Max. optical density

3.8 Dmax

Interface

USB 2.0 Hi-Speed, IEEE 1394a

Max. scan area

216x297mm (A4, Letter)

Power supply

Built into the case

Slide adapter (TPU)

Active slide-adapter built into the cover.
A set of frames for 35mm films, 35mm slides, 120/220 (6x9cm)/4x5” slides

Automatic document feeder (ADF)

None

Reliability (MCBF)

30,000 cycles

Dimensions

304x476x134mm

Weight

6.7kg

Approximate pricing

$449

I’d like to single out such model features as an improved range of optical densities, to 3.8 Dmax (the Perfection 3200 had this parameter equaled to 3.4 Dmax) and a bunch of specialized technologies. This device is the first scanner from EPSON to use Digital ICE technology, a software and hardware system for automatic image retouching. It is intended to automatically identify and remove such defects of the original as scratches, fingerprints, dust and so on. I dedicate a separate section to this technology in this review where you’ll learn its working principles at more length.

At first sight, we may seem to deal with a professional scanner, but the EPSON Perfection 4870 still belongs to the SOHO category. Until recently, there has been a distinct separation line between two classes of equipment: consumer and professional. But technologies keep on leaking from the professional to the consumer niche, thus giving birth to a kind of in-between class of devices unofficially referred to as “prosumer”. The EPSON Perfection 4870 certainly fits into this group.

In order to improve the scanning quality, the scanner uses a six-line CCD array with microlenses above each of its sensors. Thus, light is falling on the array and is then projected onto the most sensitive area of the photo-receptor, its center, allowing for a more efficient conversion of light energy into electrical one. This technology comes under the name of On-Chip Microlens and is considered a kind of revolution by the manufacturer. To improve the scanning resolution without diminishing the size of the photosensitive element, the EPSON Perfection 4870 uses two arrays (the Matrix CCD technology), shifted by half a pixel against each other. This approach allows avoiding noise in dark areas of the image.

The price of the new EPSON Perfection 4870 is set a little higher than that of the ex-flagship Perfection 3200 model: $499 against $399. I guess you’re interested to know what useful properties of the model you purchase for this money. Let’s open the box up and take a look inside.

Package and Accessories

EPSON packages all its products into beautiful boxes designed in a violet color scheme. The box has a handle for you to carry it home on your own. These are things you find inside:

Design Features

The EPSON Perfection 4870 meticulously follows the design of the previous top model, not only in the case shape, but also in the color scheme. The case is made of stiff plastic with decorative insertions of dark Plexiglas. There are locks for protecting moving parts during transportation: one of them, a big cap with a slit, is at the left panel of the case. It’s quite difficult to rotate it to unblock without a tool (like a coin, for example). The second lock is under the hood, protecting the integrated slide-adapter. All locks are wrapped in stickers that warn you about the need to unblock before use. The interface connectors are also hidden beneath such stickers that remind you about installing the scanner software before attaching the device to the computer. You had better do as they say because otherwise you’d be running the risk of damaging the device’s mechanics or spend more time for installation.


Transportation locks

The power button and the programmable button for launching your favorite scanning program are placed on the scanner’s front panel next to the scanner’s activity LED and an indicator of the slide-adapter status.

The scanner’s bed has rulers around the perimeter with dimensions of standard formats of the original. Note that although the edges of the bed are slanted to the glass (for easier extraction of the original), they have a gap in some places where a photograph may accidentally get into. I have recently had a look at the EPSON GT-15000 scanner whose bed has no such problems at all and can be set as an example for this class of devices.


Interface connectors

Like the Perfection 3200, this scanner is equipped with two high-speed interface connectors: USB 2.0 Hi-Speed and IEEE1394a (FireWire). As usual, you only receive a USB cable with the device and have to buy a FireWire one separately.

The availability of two connectors certainly allows for an easy connection to any modern computer, but you shouldn’t be misled to think that the EPSON Perfection 4870 can be attached to two computer systems at a time. This scanner is intended for individual use and comes without any communication adapters.

Slide-Adapter

I could talk long about how much the new scanner is better than its predecessor and whether the innovations cost the extra $100 you count out for the new device, but I’m sure nobody will ever state that the EPSON Perfection 4870 is just a cosmetic improvement on the past product. Changes in the hardware stuffing are of a global nature and the similarity to the Perfection 3200 goes no further than the common design of the case. As for the qualitative changes that account for the EPSON Perfection 4870 to have made a step forward compared to its predecessor, they mostly refer to the integrated slide-adapter or, as EPSON calls it, the transparency unit. Having optimized the spectral characteristics of its lamp, the manufacturer can now honestly talk about an improvement of the optical density range from 3.4 to 3.8 Dmax.

The EPSON Perfection 4870 uses an active adapter for scanning transparent originals, which is placed in its lid. The slide-adapter and the scanner are coupled together by means of a cord attached to the appropriate connector at the device’s rear panel. The lamp of the Perfection 3200 model used to shine through the slides was realized as a solid luminescent surface occupying all the useful perimeter of the lid. The slide-adapter of the EPSON Perfection 4870 is made as a moving carriage with the light source installed in it. The use of the carriage and the moving mechanism explains the fact that the Perfection 4870 has a bit thicker lid than the Perfection 3200.


Frames for films and slides

In the standard situation, when the scanner is used for digitizing photographs, the slide-adapter is shut behind a special cover. You remove this cover for working with transparent originals and install frames for films and slides on the glass of the bed. As I mentioned above, these frames are intended for originals of all sizes and formats, including the rarest ones.

A series of perfected technologies whose origin can be traced back to machines of earlier generations is employed in the EPSON Perfection 4870 for better scanning of transparent originals and to increase the speed of digitizing. For example, the manufacturer had to polish off the Dynamic Range Control system to optimize scanning of negatives whose masking layer doesn’t easily let pass the blue part of the spectrum. In earlier models, this system used to reduce the scanner’s speed as additional time was required for the blue filters of the CCD array to receive enough light. The EPSON Perfection 4870 solves this problem: the blue component in the spectrum of the slide-adapter’s lamp is intensified to increase the scanning speed, although not very much. And if you enable the software-hardware technologies of dust removal, the scanning speed degenerates in times. On the other hand, the manufacturer emphasizes exactly these technologies saying the Perfection 4870 to be a breakthrough in the scanning quality area. I will deal with these technologies right now, in the next section of the review.

Digital ICE and Dust Removal: Dust Won’t Pass!

It is the first time that EPSON implemented in its scanners the software-hardware system called KODAK/ASF Digital ICE and developed by engineers from Kodak’s Austin Development Center (this division is known under the name of Applied Science Fiction). Digital ICE technology is not new and has long been employed in specialized scanners from other manufacturers but the very fact of its use in a SOHO-class device, the EPSON Perfection 4870 is, is a kind of novelty by itself.

This system deals with various image defects caused by dust, scratches and so on (i.e. physical defects of the original). The system works with transparent (Digital ICE for Films) as well as with opaque (Digital ICE for Prints) types of the original. Let’s learn some specifics about this technology.

Processing Films: Digital ICE for Films

It is no secret that the scanning of slides requires great care. It’s very hard to make the surface of the original absolutely pure: ubiquitous specks of dust are literally attracted to films, thus making necessary the time-consuming post-processing of the scans. A dust mote, quite invisible to the eye, transforms into an elephant in a high-resolution scan. If you’ve ever tried it, you know that the standard way of dealing with dust (in an image-processing program) takes much time. The Digital ICE for Films technology solves this problem to some extent. When scanning transparent originals, this technology uses a fourth additional channel called defects channel. To reveal mechanical damages on the film and gather information about them, the surface of the original is once again scanned in the infrared range. With this info on hands, the computer performs image retouching, but only on the damaged areas. Digital ICE for Films doesn’t work with usual black-and-white films as well as with Kodachrome 64 Professional films.

Processing Photographs: Digital ICE for Prints

Digital ICE for Films may be considered as a technology “ported” in the “as is” way from specialized slide-scanners, but Digital ICE for Prints employed in the EPSON Perfection 4870 PHOTO scanner is “native” for flatbed scanners. It allows working with opaque originals, finding dust, scratches and other physical defects. As I mentioned above, films are scanned in the infrared range to reveal such defects. Photographs are dealt with in another way. The scanning process takes two passes with two light sources for photographs. The surface is illumined with two light sources positioned under different degrees and reflects different shadow patterns, depending on the artifacts of the original. This information is then given to the computer which finds and compares discrepancies and performs necessary retouching.

Dust Removal: Software Cleanup

Besides the hardware technology for cleaning the image up, the EPSON Perfection 4870 uses another method of avoiding mechanical defects, using the software Dust Removal technology. By the way, you should note that Digital ICE is the only of the two technologies to work with snapshots. Then, Digital ICE is better at removing defects, but it needs more resources and time than Dust Removal. Besides that, Digital ICE doesn’t support certain types of film like black-and-white negatives, very popular just a few years ago. The user can choose the necessary method depending on his/her own demands on the quality and speed of scanning.

You enable the above-described technologies in the exclusive scanning program, which is described in the next section.

Scanning Software: EPSON Scan

EPSON traditionally supports its scanners with unified software, tailoring it for the specific device. The powerful and universal scanning program, EPSON Scan, doesn’t practically change from model to model. Its main concept is in allowing the user to choose the scanning mode depending on the user’s own experience. Someone will be satisfied with the simplest mode, while an advanced user may want to set up each parameter manually. The EPSON Perfection 4870 offers three modes:

Full Auto Mode


Full Auto Mode is the simplest and fully automatic mode

This mode doesn’t require anything from the user. The device itself determines the size of the original by performing pre-scanning and then accomplishes the final phase of digitization. The user can only set up the parameters of the resulting file and choose a few options.


The auto-scanning preferences window

As you see, you can identify the type of the original, set up the resolution (the highest is 1200dpi for this mode) and enable the software Dust Removal technology. Anyway, that’s not little, don’t you think?

Home Mode


Home Mode offers enough settings for a majority of users

Home Mode offers more flexibility – it is intended for people who already know something about scanning. The maximum resolution in this mode is 4800dpi and that’s quite enough for many applications.


You can enable a few intelligent technologies
in the Image Adjustments window

You set up the scanning parameters by selecting the type of the original and finish it by turning on some special functions in the Image Adjustments window.


Color Management

Besides choosing the working folder, you can control the color. In this window you can choose the gamma compensation, assign ICM profiles or disable the automatic color correction at all. The window with these settings is analogous to the one of the professional mode.

Professional Mode

If the two above-described modes don’t suit you, and you feel yourself experienced in the scanning field, here’s your mode in which you set up all digitization parameters manually. For easier navigation, the parameters window is divided into three thematic sections: Original, Destination and Adjustments.


The Original section is for selecting the type of the original


The Destination section is for choosing the parameters
of digitization quality and dimensions


The Adjustment section is for activating
additional image correction tools

There are four icons in the section that contains image correction settings. The first icon looks like a sphere – it activates the Auto Exposure function. The result of this function is immediately displayed in the preview window.


Histogram Adjustment

The second icon displays a histogram. You click it to open the Histogram Adjustment window where, unlike with the Auto Exposure function, the user can manually set up the level of each color channel. This function is analogous to the Levels conversion in Photoshop.


Tone Correction

The third icon opens up the tone correction window. This function is analogous to the Curve tool in Photoshop with only one exception: here we have a number of presets of varying brightness and contrast.


Image Adjustment

The last icon serves for adjusting the color balance of the image, if it is somehow shifted.

The Adjustment section contains the following functions:


A scan of a magazine sheet without application
of the Descreening filter


A scan of a magazine sheet with the Descreening filter
and a linage of 175lpi

Besides the scanning program, the CD you receive with the Perfection 4870 contains several exclusive utilities for making your interaction with the device easier. You can launch the programs as you do any other software, but you can also do it with the programmable Start button on the face panel of the scanner. By the way, the designers chose the right place for the button as it is on the level with the case – you can’t press it accidentally. This button starts the EPSON Smart Panel by default, but you can reprogram it to launch any of your favorite programs. I guess this button is better assigned copying of documents and sending them to the printer without launching any applications.


The Smart Panel helps you make up your mind as to
what you want from the scanner

The Smart Panel is a nice place for doing all scanning tasks like copying, scanning for the Web or into a file, or into an application or whenever you wish.


Copy utility

There are many exclusive utilities with a user-friendly interface that EPSON has parceled for the user – I just can’t describe them all in a single article. Just take a look at the interface of the Copy Utility which copies the look of the LCD display of a copier machine.

Testbed and Testing Methodology

The EPSON Perfection 4870 scanner turned to be an exciting machine and it took me some time to get determined about the testing methodology. After some consideration, I decided to test the scanner in several phases, attaching it to a testbed that was configured as follows:

Actually, you need a very powerful computer for a scanner with so high declared values of the optical resolution. Otherwise, any scan operation threatens to become never-ending, playing on your nerves. Moreover, Digital ICE technology needs additional system resources to work properly. The following table shows how much system memory and free disk space you need to scan photos and films with Digital ICE enabled:

Dimensions and type of the original

Resolution

HDD space required

System memory required

6” x 4” (152 x 102 mm) photo

600dpi

157MB

185MB

4800dpi

626MB

370MB

A4 (210 x 287 mm) photo

600dpi

631MB

255MB

4800dpi

2524MB

510MB

35mm film

150dpi

1MB

8MB

300dpi

1MB

15MB

600dpi

4MB

30MB

1200dpi

16MB

59MB

2400dpi

63MB

117MB

3600dpi

142MB

175MB

12800dpi

251MB

233MB

Medium format (114 x 56 mm) film

150dpi

4MB

34MB

300dpi

8MB

70MB

600dpi

29MB

139MB

1200dpi

116MB

277MB

2400dpi

464MB

553MB

3600dpi

1042MB

830MB

12800dpi

1853MB

1106MB

4” x 5” (94 x 118 mm) film

150dpi

4MB

36MB

300dpi

13MB

72MB

600dpi

51MB

144MB

1200dpi

202MB

287MB

2400dpi

805MB

573MB

3600dpi

1811MB

859MB

12800dpi

3219MB

1145MB

The resolutions shown in the table are actual resolutions supported by Digital ICE. These values may differ from those you may want to use in the scanning program. In such cases, conversion occurs. For example, if you have selected 200dpi, the scanning for Digital ICE will be done with 300dpi and then converted into 200dpi.

In any case, this table will help you estimate the capabilities of your computer – maybe you should consider upgrading before purchasing the Perfection 4870?

Digitization Speed

One of the key characteristics of any scanner is its ability to quickly process originals of any degree of complicity. Requirements to the speed qualities of the scanner are high, but if I’m not mistaken they are not regulated by any official norms and standards. This may be the reason for the manufacturers to declare only those speed values which won’t shock the potential buyer. The digitization speed of a scanner depends on several factors. I’ll try to enumerate them.

The configuration of the system the scanner is attached to is of highest importance. The amount of main memory and the free disk space are both very important. To improve performance you’d better place a second hard disk drive on the second IDE channel for it to receive the digitization data.

The type of the interface to the computer is also a key contributing factor to the scanner’s digitization speed. All modern devices are equipped with high-speed USB 2.0 and FireWire ports so you should make sure your system has them. I think a FireWire connection is preferable as it doesn’t require a controller (FireWire works by the “peer-to-peer” principle) and consumes fewer resources than a USB connection.

The third factor is the speed of the scanner proper. It greatly depends on the light source employed in the particular scanner. Traditional mercury lamps used in a majority of SOHO scanners need additional time to warm up. This time is necessary for the mercury to transform from liquid into gas for the light to be evenly distributed. To my regret, the EPSON Perfection 4870 uses such a lamp, too. There is an alternative to mercury – xenon lamps – and maybe we’ll see one employed in the next top model from EPSON?

Now, let’s get back to our tests. After the user activates scanning software, the machine should carry out the pre-scan operation. The lamp warm-up time is about 25 seconds in this phase.


The mercury lamp may take from
25 seconds to 2 minutes to warm up

The lamp warm-up time may differ greatly between the tasks. For example, this time is much higher for scanning transparent originals. Note that when you are scanning using Digital ICE technology, the lamp warms up several times, which results in a much higher overall scanning time.

Speeds of digitizing different originals

 

300dpi

600dpi

4800dpi

6” x 4” (152 x 102 mm) photo

12s / 1m 30s

23s / 1m 35s

11m 45s / 12m 20s

35mm film

18s / 1m 55s

25s / 2m 20s

1m 40s / 8m 20s

A4 size (210 x 287 mm) photo

38s / 3m 25s

50s / 3m 45s

- / -

I measured the digitization speed in three resolutions: 300, 600 and 4800dpi. As you see, the table shows two values for each mode – the second value is measured with Digital ICE enabled. I didn’t perform the measurement for the A4 original at the optical resolution, because this operation would not only require about 3.5GB of disk space, but would also take much time. This phase of my testing was too long as it was, so I didn’t scan originals of other types and formats.

By the way, you can calculate with some precision the size of the file you receive at high resolutions. Use the following formula:

S = k∙L∙H∙R­­2,

where S is the image size (in bytes), L is the length of the original (in inches), H is the height of the original (inches), R is the scanning resolution (dpi) and k is a fixed coefficient. This k equals 3 for the Color scanning mode, k = 1 for the Gray mode and k = 0.125 for the LineArt mode.

Scanning Quality

Scanners with a CCD array differ from CIS-array ones in the depth resolution in the first hand. This feature allows for creating sharp images of centerfolds of thick books and magazines – for the character recognition software to work properly on them. Another application of this property of CCD scanners is making “snapshots” of volumetric items like printed circuit boards, complex relief objects and so on. In fact, you can make a collage of various objects right on the scanner’s glass. As an example, I placed a few felt-tip pens on the bed of the Perfection 4870 and scanned them.


Click to enlarge


This scan confirms the big depth resolution of the device

Of course, such scanning of volumetric objects is of merely academic interest. The EPSON Perfection 4870 is sharpened at digitizing transparent originals, so we should pay much attention to this aspect.

So, this scanner is equipped with an advanced and powerful tool – the hardware and software complex called Digital ICE – and I couldn’t help checking it out. First of all, I checked out the Digital ICE for Films technology. Dust is an annoying thing when you’re scanning slides – it makes you spend much time for post-processing images in an appropriate program.

So I took a Kodak Ektachrome E100S slide for the 120/220 frame. I didn’t specially put dust onto the film surface – there’s enough dust flying around our test lab. Below you can see three fragments of the slide scanned with and without the dust removal technologies. I selected the maximum optical resolution, i.e. 4800dpi. It is in this mode that like under a microscope the slide shows all of its smallest dust motes.


The dust area is marked with red – its fragments are shown below


The slide fragment scanned without dust removal technologies

The first fragment shows what’s here to be seen. Dust is on the surface of the slide like a host of malicious microbes.


The same fragment, but scanned with Dust Removal enabled

Yes, Dust Removal works all right, but it didn’t wipe all the dust away. This software technology left a scarcely visible scar on the image – the trace of interpolation.


That’s the work of Digital ICE for Films. Feel the difference!

The third fragment shows you the result of using Digital ICE for Films. There’s practically no dust left, including the dark specks at the bottom of the fragment. Interpolation is performed at a higher level, using image antialiasing functions. Yes, the result is astonishing, but you should be aware that Digital ICE for Films has certain drawbacks, one of which is incompatibility with some film types. Kodak says only Kodachrome 64 Professional is such, but it doesn’t mean they have tested all existing types of films in their labs. You’ll see below this technology giving an incorrect result.

So far, let’s have a look at the quality of digitizing of an average-format transparent original scanned with the maximum optical resolution:


A scan of average-format Kodak Ektachrome E100S film


A fragment of this scan in its actual size

Next goes an example of the digitization of color negative Fuji S-100 film, with and without Digital ICE for Films.


The scan of color negative film


This scan is made without Digital ICE


This is the result of enabling Digital ICE

The quality of scanning black-and-white negative film will be exampled by the following image, digitized at the maximum optical resolution (4800dpi) with 48-bit color depth (in the color scanning mode). This is Kodak 5052 TMX film.


A scan of black-and-white negative film

The film grain is distinct at such a high scanning resolution. That’s the reason for me to use the Grain Reduction technology to show you the results of its work.


A scan without Grain Reduction


Another scan with Grain Reduction applied

I think this example is good at showing the effect of this technology. Note though that Grain Reduction noticeably reduces the image’s level of detail, so I won’t say it’s a perfect tool. You can do something much similar using the Blur filters in Photoshop, but what if you have numerous films to process?

The next example shows the quality of scanning color positive film. This time I’m interested not only in the quality of digitizing as it is, but also in how well Digital ICE for Films works with it.


Pay attention to the marked-out areas

After scanning with and without Digital ICE, I found out that this system is incorrect at working with my film (it was color positive Fuji RAP 100F film taken at random). The arrows show the areas of the snapshot which were considered by the system as if dirty, although there was no dirt there on the original. Thus, Digital ICE for Films is incompatible not only with Kodachrome 64 Professional, but with some other types of film, too. I guess additional info about compatibility should be sought on topical forums.

The next example shows the effect of the color restoration system:


That’s how color restoration works

Regrettably, I had no faded-out snapshot or slide on my hands, so I took normal (fresh) film. As you see in the figures above, the scanner’s color restoration technology works correctly. Note that the sky and the earth both have the natural color. My friend, a professional photographer, liked this result, too.

Now you can visually evaluate the quality of digitizing three types of originals: three color targets Kodak IT8.7/2 Q-60. The scanning parameters were set up in accordance with the three basic modes available in the exclusive EPSON Scan utility.

Image Noises

Noise appears in the image as a result of impurities in the useful analog signal of the light-sensitive sensor of the scanner. This only happens on the earliest phase when low-power electrical signals are transferred to the analog-to-digital converter – that’s where the signal is the most vulnerable. Such noise distortion may be random or correlated. The difference between the two phenomena allows dividing my testing of the noise into two steps.

Random Noise

The graph below shows the dependence of the random noise value on the reflecting capability of the areas of the Kodak IT8.7/2 Q-60R2 target. It’s clear that the signal level of the first part of the scale (white) will always be higher than that of the last part (black), while the deviation value may sometimes be random. The signal-to-noise ratio should be regarded as “the more – the better”. Thus, higher SNR values indicate that the scanner is tolerant to noise.


The graph shows the dependence of the random noise
value on the reflective capacity of the original

The next graphs allow estimating the value of relative color deviations of two scanners: EPSON GT-15000 and Perfection 4870. I used a scan of gray target as a test sample, digitized by both scanners with the same parameters. Ideally, the RGB values should equal each other, producing a straight line.


Color deviation of the EPSON GT-15000 scanner


Color deviation of the EPSON Perfection 4870 scanner

As we might have predicted, the Perfection 4870 shows much better results than the office scanner. Well, the two devices clearly have different purposes.

Correlated Noise

Unlike random noise, which shows itself as “snow” in the resulting scan, correlated noise is distinct and complies with a certain law. It can show up as stripes, regular raster patterns or diagonal, vertical and horizontal lines (in relation to the lines of the raster). Any form of correlated noise is easily recognizable visually.

The vertical form of correlated noise (Streak Noise) has its origin in the CCD technology itself. The scanner’s lamp has unstable light intensity. Added the electrical pickups of the photosensitive array, the image may acquire noise, correlated to the raster lines. The diagonal correlated noise may appear because of parasite influence on the useful signal, which is being transferred from the digital device to the analog (for example, as a result of the digital timer and the moving mechanism of the scan carriage getting out of sync). Such noise is called crosstalk. As you see, there are many noise-creating factors, and we can estimate them in numbers. Using out methods of testing SOHO scanners, we created the following table:

 

Correlated noise

Row-correlated noise

EPSON Perfection 4870

27.62

36.09

EPSON Perfection 3200

39.83

43.11

EPSON GT-1500

23.87

39.13

This table allows making judgments about the tolerance of the electronics of the scanner to noise. However strange, the EPSON Perfection 3200 showed the best results. The explanation of this fact may lie in differences in the electronic stuffing of the machines.

Profiling

This section of our tests is concerned with determining the color range of the scanner. The qualitative parameter of the color correspondence allows estimating how far the colors deviate from the specified values. There are several programs that allow doing this – they support color targets of the IT8/7 standard. We can estimate the color deviation of the scanner by translating the measured values of each area of the color scale of the target into a data table and comparing it with the data from the manufacturer of the target.


EPSON Perfection 4870: Color Range

The color space of the tested scanner is translated to conform to the industry-standard sRGB color space. Comparing the color range of the Perfection 4870 with that of the GT-15000 scanner, we may notice that the Perfection has a much larger space. This fact is due to the different proposed sphere of application of the devices (the EPSON GT-15000 is a purely office machine, while the Perfection 4870 was designed for scanning photographs and slides). The high value of the optical density range and the optimized light spectrum of the lamp of the Perfection 4870 result in a large color space – it might have been clear without any measurements. Anyway, the results of this phase will be required later, when we test newer scanners.

The color difference parameter, Average deltaE*, was 0.48. This is an indication of a good color balance. The maximum peak on a given color plate was 3.15; the minimum level was 0.03.

After measuring the color range and the color difference parameter, I created a file with an ICM profile. This file can be applied to a scan, digitized without color correction, directly in an image-processing program (the driver allows doing this). The examples follow:


You can apply an ICM profile to the scan in Photoshop


The scan without color correction


The same scan, but after application of the color profile in Photoshop

The difference is clearly seen with a naked eye. After I applied the profile to the scan, the color became more vivid and closer to the colors of the test target.

I guess we’ve had enough testing for today. Now I’m only going to express some points about the EPSON Perfection 4870 scanner:

Highs:

Lows:

Conclusion

Winding up this review, I’d like to put down a short resume about the reviewed device. The EPSON Perfection 4870 scanner undoubtedly complies with the highest standards of quality. All its parts are easily accessible, including the connectors at the rear panel. The scanner is well-designed in full accordance to the laws of ergonomics and is easy to use. The slide-adapter is compact, but the lid has become too heavy because of the adapter and you cannot open it by a half – the hinges are not stiff enough to support the weight of the adapter. I guess another fastening is required now.

I enjoyed not only the scanner proper and its accompanying software, but also the selection of frames for transparent originals. Well, many users will probably only use the frame for 35mm films. All frames are made of stiff plastic, their locks are caring about the film. They take all the useful space on the scanner bed, thus speeding up the process of scanning a series of materials. You can get into a film-digitizing business with such frames!

My respects also go to the engineering team from EPSON for placing the Power On button on the front panel, next to the Start button. Many scanners have this button at their butt – it is not very easy to access then.

Beyond doubt, the EPSON Perfection 4870 is an excellent scanner that will satisfy a majority of users. It is fast and meticulous about colors at scanning reflecting originals. The quality of scanning transparent originals is on a highest level, too, so I think you’ll hardly tell between the work of the Perfection 4870 and that of a professional slide-scanner, particularly with average and large-format slides. At the same time, the price of the Perfection 4870 is much lower than you’d have to shell out for an average-format slide-scanner. The Digital ICE system is good, too. This technology helps saving much time you used to spend on post-scan retouching.

I hope EPSON will replace the traditional mercury lamp with a zero-warm-up lamp in their next flagship product as this is the only thing you can gripe about here. Anyway, this scanner would win all nominations in my personal contest of contemporary SOHO scanners. The EPSON Perfection 4870 is our choice and the test results confirm that. I guess all other scanners for home and office use now have a new beacon before them: the EPSON Perfection 4870 has raised the bar very high!