How colors are converted between different ICCs

The International Color Consortium stipulates that colors can be converted between different ICCs in four ways: perceivable, saturation, relative chromaticity, and absolute chromaticity (both in the photoshop color management panel and in the conversion to the profile panel. turn up).

Perceptual rendering intent

This is the most commonly used conversion method. This method changes all colors in the source device's color space while keeping all colors invariant, but leaves all colors in the overall sense unchanged.

This is because our eyes are more sensitive to the interrelationships between colors and are less sensitive to the absolute value of the colors. If an image clearly contains some extra-gamut colors, the use of perceptual reproducibility is a good choice. It is more suitable for the relatively small CMYK color gamut conversion of the RGB color gamut of the sedan.

Simple understanding: It 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.

Saturation rendering intent

This method tries to maintain the vividness of the color without much concern for 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. This method is suitable for copying of various charts and other business graphics, or for making maps marked with color height or depth, as well as cartoons and comics.

Simple to understand: keep it bright, but the colors will not be accurate.

Relative colorimetric rendering intent (media-relative colorimetric rendering intent)

Relative chromaticity is to accurately replicate all colors in a good domain, crop out the colors outside the gamut, and convert the cropped colors to their closest reproducible colors. The relative chroma reproduction intent is a better choice than the perceived rendering intent for image copying because it retains more of the original color. Suitable for the conversion of ICC between the gamut is not too large, such as: Japan's pre-CMYK icc converted to the United States icc.

Simple understanding: try to meet the original. The advantage is that most colors do not change, but the disadvantage is that the individual colors that go beyond the color gamut change greatly.

Absolute colorimetric (ICC-absolute colorimetric rendering intent)

Absolute chromaticity does not map the white point of the source device's color space to the white point of the target device's color space. If the white color of the source device's color space is blue, and the white color of the target device's color space is slightly yellow, when using the absolute color reproduction intent, it will add some blue ink to the output white area to simulate the original white color. The absolute color reproduction intention is mainly designed for proofing, and the purpose is to simulate the copying effect of the final output device on another proofing device.

Simple understanding: simulation paper white, white changes greatly. It is not suitable for general conventional conversion. It is only used in rare situations and it is not necessary to master it.

All the conversions between different ICCs must follow these four conversion methods and there is no other choice. At the same time, when we convert the image of the icc file, it is best to look at the different conversion methods to bring the image of what changes, from which to choose the most suitable for the existing image conversion.