The intention of the color space in print

We often find ourselves confused about the selection of rendering intents in color space conversion when we are creating problems with the printer's icc curve. Therefore, the differences in the four conversion intentions of the color space can be compared more intuitively through the illustration.

In general, the actual device's color gamut is not enough to reproduce the source space color, that is to say the target space is smaller than the original space, of course, this is not what we expected, but it is often the case, how to deal with colors beyond the target color space, this This is the origin of the problem of the coloring method. Icc provides a total of four coloring schemes, or gamut mapping methods to deal with this problem, each method is a compromise and compression, the problem is how to choose. These four methods were translated in photoshop Chinese version as perceptual, saturation, absolute colorimetric, and relative colorimetric.

Perceptual intent

Perceptible is the most commonly used conversion method. The perceptual conversion method is to change all the colors in the source device color space while keeping all the colors invariable, but to keep all the colors in the overall feeling unchanged.

Our eyes are more sensitive to the interrelationships between colors, and are less sensitive to the absolute value of color. If an image clearly contains some extra-gamut colors, adopting perceptual intent is a good choice. It is perceptually more suitable for the relatively small cmyk color gamut conversion of the rgb color gamut of the sedan. Popular understanding can be called overall compression. The advantage is that the contrast relationship between all the colors on the image can be maintained. The disadvantage is that each color on the image changes, and it can often be seen that the overall image becomes lighter.

This method can be said to take into account the advantages of colorimetry and saturation, designed to preserve the visual relationship between colors, although the color value itself may change, but the human eye looks more natural, this program due to maintain the original The color relationship is proportional compression, so it is suitable for high quality photographic images.

Saturation (saturation intent)

Saturation is actually a kind of linear compression. The saturation conversion method tries to maintain the vividness of the color and ignores the accuracy of the color. It maps the most saturated color in the source device's color space to the most saturated color in the target device. The advantage is that all the relative relationships of colors have not changed and the hierarchy has been preserved; however, the disadvantages are also obvious. That is, all colors are changed, saturation is reduced, and the common understanding is to maintain the vivid colors of the images and lose the accuracy of the colors. .

Because saturation loss in this method is the greatest, the saturation loss method may be more precise. It is more suitable for applications that need to resolve the relative relationship of colors, such as scientific images, business charts, etc., such as dna staining images, or photographing Mars infrared photos, because the specific colors of these applications are not important, and it is more important to distinguish color differences.

The simplest is the colorimetric intents, which keep the colors in the target gamut unchanged, at the expense of color outside the gamut. The colorimetric method is divided into two types, one is the absolute colorimetric comparison of the icc, and the other is the relative colorimetric method associated with the output medium.