Color and Multiband Processing

Plugins for color space conversion and processing of color/multiband images. Note that in context of color/multiband processing a multiband image is understood as a stack of gray level images.

Additional plugins for color calibration and color space conversion are available in ijp-color project.

Plugins

• RGB to CIE L*a*b* stack - Converts image pixels from sRGB color space to CIE L*a*b* color space. Uses fixed formulas described at Bruce Lindbloom Math section. The output is a stack of floating point images (GRAY32). L* band in in the range 0 to 100, a* from -100 to 100, and b* from -100 to 100.

• RGB to XYZ stack - Converts image pixels from sRGB color space to CIE XYZ color space. Uses fixed formulas described at Bruce Lindbloom Math section. The output is a stack of floating point images (GRAY32).

• CIE L*a*b* stack to RGB - Converts image pixels from CIE L*a*b* color space to sRGB color space. Uses fixed formulas described at Bruce Lindbloom Math section. It assumes that the input is a stack of three floating point images (GRAY32), corresponding to L*, a*, and b*, respectively.

• XYZ stack to RGB - Converts image pixels from CIE XYZ color space to sRGB color space. Uses fixed formulas described at Bruce Lindbloom Math section. It assumes that the input is a stack of three floating point images (GRAY32), corresponding to X, Y, and Z, respectively.

• RGB to YCbCr stack and YCbCr stack to RGB - Conversion between RGB and YCbCr color spaces.

• Measure Bands - Measure bands of color (RGB) image or slices in a stack recording results in a single row. If image is 8-bit gray, 16-bit gray, or 32-bit gray, each slice is measured and results reported in columns of the same row. If image is an RGB then only the current slice (if more than one) is measured. Column names are the names measurements prepended with slice labels.

  Reported measurements can be selected using Analyze > Set Measurements. Supported measurements include: area (ROI), centroid (ROI), mean, standard deviation, mode, min, max, median, skewness, and kurtosis.

• Multiband Sobel edges - Sobel edge detector that supports multiband and color images, also work on gray level images. A multiband image is understand as a stack of images in which each slice corresponds to different band. That is, each pixel is understand to have a vector of values (number of elements in the vector is equal to rack size or to 3 in case of RGB images). The operation is similar to a typical Soble operator, however, the distances between pixel intensities in the original Sobel operator are interpreted as distances between pixel value vectors.

• Multiband difference edges - Finds edges in a multiband image by computing maximum Euclidean distance within 3x3 neighbourhood. The distance is computed between opposite pixels in the neighbourhood, that is four different distances are compared.

• Multiband gradient edges - Finds edges in a multiband image by computing maximum Euclidean distance between the center pixel and each of the other pixels in a 3x3 neighbourhood. That is, eight different distances are compared.

• Intensity shift - Shifts (wraps around) GRAY8 image intensity. It is useful, for instance, for 'shifting' the intensity in H band of an HSB stack.

The plugins are available under Plugins > Color menu, brief help for each plugin is available under Help > About Plugins menu.

Related Plugins

• ijp-color plugins
• k-means clustering plugin
• 3D Color Inspector plugin