Thanks to Julio Marchi for this space in MSX All

Color Magic

  The Magic Color project aims at developing an extra tool for MSX Viewer project to perform image color changes.

  1. Introduction
  The Color Magic tool came up as an alternative program that could perform image colors changes. For example, suppose that we want to change all the cyan objects (index 7 on MSX 1) on an image to gray (index 14 on MSX 1).
  The developed prototype could do that and even better: it is possible to select objects using ranging color values and change their R,G,B values. In addition, it is possible to change objects inside a selected area instead of the whole image.
  MSX Viewer 5 brings this color tool feature, but only works with solid colors and changes on the whole image.

  2. The Prototype
  The developed prototype works with 24-bit images, allowing the change of solid color or ranging colors values from objects.


  If the user wants to select objects from an image using ranging colors values, he selects a rectangular area on the image which is used as a "sample" area to define the colors limits. For example, he selects an area from a human face an clicks on "Amostra" (sample) button. Then, the minimum and maximum R,G,B values are registered to limit the colors used for selecting objects.
  Such type of color selecion is not common on image editors. For example, "the Gimp" selects pixels on contiguous areas or on the whole image based on the sampled pixel plus a given tolerance, but not using the initial and final colors defined separatelly.

  The next example depicts the color change on a game screen using the prototype.

Original image Modified image

  3. Current version in MSX Viewer 5
  A tool for changing solid colors was incorporated in MSX Viewer 5 at the "Color recognition" stage. The option "Analysis" opens the histogram tool, which also features three options for changing colors.

  Available options:
  - Change indexes - only change two color indexes without changing the colors on the image.
  - Change colors - change two colors on the image.
  - Join colors - put two color indexes together in only one.

  The option "change colors" is what the prototype does.
  This new tool is compatible with MSX 2 and V9990 palettes.

  The MSX Viewer 5 palette tutorial details more the "Analysis" tool.

Marcelo Silveira
Systems and Computing Engineer
Expert in Image Processing and Artificial Intelligence
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