X-bit labs

EPSON Perfection 2480/2580 PHOTO: Fall Offsprings in the “Perfect” Family (page 6)

Category: Other

by Sergey Samarin

[ 09/27/2004 | 09:01 AM ]

Profiling and Gamut Ranges

This section is concerned with evaluating the error in the scanner’s interpretation of the colors of the original IT8.7/2 color target with the help of a color management system. In other words, we will know the coefficient of the color distortion introduced by the scanner into the image. Below there are gamut range diagrams for opaque (reflective) and transparent (emissive) originals.

The gamut ranges of the scanners when processing opaque originals

The gamut ranges of the scanners when processing transparent originals

The gamut range identified as a triangle in the diagrams is a projection on the plane and determines the scanner’s palette in the visible light spectrum. Since we know the coordinates of the vertexes of the triangles, we can calculate their areas to estimate the absolute values of the ranges.

Gamut squares of the scanners

For the comparison’s sake, I also offer the squares of the triangles for the standard sRGB and Wide Gamut RGB color spaces (the former is used with he majority of monitors, and the latter reflects the maximum area in the CIE La*b* space). Besides that, I added the information on the gamut squares of the two scanners taken from the manufacturer’s profiles.

The next diagram is constructed by calculating the difference between the colors of the original target and its scan. Note that Color Difference values above 5.0 are discernable by most people, i.e. evident for the “average” human eye. 

The closer to the X axis – the better

The diagram shows that most color-reproduction errors fall on the darkest areas of the color scale, starting from the GS17 point. And this only concerns reflective originals, while the delta E values remain in the acceptable range when scanning films.

Conclusion

You have witnessed a quite successful debut of the new models of the EPSON Perfection series that came to replace the popular Perfection 1670 model. The new products passed all my tests with honors; you can compare them with earlier-tested devices by referring to our previous reviews. I would like to emphasize the excellent design of the film auto-feeder of the Perfection 2580 as well as the real simplicity and the ease of use of both devices. With all the useful qualities of the Perfection 2480 and 2580 PHOTO scanners, I can’t but recommend them to your consideration.