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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:

  • Highest scanning quality;
  • Digital ICE technology for scanning transparent and reflecting originals;
  • Excellent frames for films and slides, including average and large formats;
  • Well-designed exclusive software;
  • Reasonable and affordable price.

Lows:

  • The mercury lamp takes very long to warm up, slowing down the scanning process (especially for films);
  • High demands on the computer hardware, especially if you enable Digital ICE;
  • Slow scanning of films;
  • No FireWire cable among the accessories.
 
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