3.2.6. Blending operators

There are several blend modes implemented and more might be added in future. For now all of the most commonly used ones are included and you will recognize a few of them from other imaging software. A good introduction on many common blend modes is given in the GIMP Manual (Chapter 8.2, Layer Modes). Therefore we only discuss a few blend modes here in more detail.

3.2.6.1. blend modes

normal

This will probably be the most used blend mode. It just mixes input and output and, depending on the opacity value, it reduces the strength of a module's effect. Generally this is also the blend mode of choice if you want to apply a module's effect locally using masks.

normal bounded

This blend mode acts similarly to blend mode normal, except that input and output data are clamped to a particular min/max value range. Out-of-range values are effectively blocked and do not pass to the following modules. Sometimes this helps to prevent artifacts. However, in most cases (e.g. highly color saturated extreme highlights) it is better to let unbound values travel through the pixelpipe in order to properly deal with them at the right place (e.g. in module output color profile). Blend mode normal is most often the preferred choice.

lightness

This blend mode mixes lightness from the input and output images. Color data (chroma and hue) are taken unaltered from the input image.

chroma

This blend mode mixes chroma (saturation) from the input and output images. Lightness and hue are taken unaltered from the input image.

hue

This blend mode mixes hue (color tint) from the input and output images. Lightness and chroma are taken unaltered from the input image. Caution: When modules drastically modify hue (e.g. when generating complementary colors) this blend mode can result in strong color noise.

color

This blend mode mixes color (chroma and hue) from the input and output images. Lightness is taken unaltered from the input image. Caution: When modules drastically modify hue (e.g. when generating complementary colors) this blend mode can result in strong color noise.

Lab lightness

Only available with modules that work in the Lab color space; this blend mode mixes lightness from the input and output images, while color data are taken unaltered from the input image. In contrast to blend mode lightness this blend mode does not involve any color space conversion and does not clamp any data. In some cases this is less prone to artifacts in comparison to lightness.

Lab color

Only available with modules that work in the Lab color space; this blend mode mixes Lab color channels a and b from the input and output images, while lightness data are taken unaltered from the input image. In contrast to blend mode color this blend mode does not involve any color space conversion and does not clamp any data. In some cases this is less prone to artifacts in comparison to color.

HSV lightness

Only available with modules that work in the RGB color space; this blend mode mixes lightness from the input and output images, while color data are taken only from the input image. In contrast to blend mode lightness this mode does not involve clamping.

HSV color

Only available with modules that work in the RGB color space; this blend mode mixes color from the input and output images, while lightness data are taken only from the input image. In contrast to blend mode color this mode does not involve clamping.

color adjustment

Some modules act predominantly on the tonal values of an image but also perform some color saturation adjustments, e.g. module levels and tone curve. The color adjustment blend mode takes the lightness only from output data and mixes colors from input and output enabling control of the module's color adjustments.