Exploring colors and grays with ImageJ

 How are stored the grays and colors in a digital image? This simple question is explored in this post thanks to the IJ programming language.

Numbers: binary, decimal, hexadecimal

Numbers used by computers and by extension by programming languages can be represented in different radix (base). Usually, the decimal notation is the most convenient - specially for human beings - but in certain circumstances, it's better to use the binary or hexadecimal notations.

Color wheel

Painters and computer artists, often use a color wheel which is composed of color hues arranged along a circle. There are some interesting features in such a presentation of this color table (also available in the HSV/HSL color space): primary, secondary, and complementary colors...

Indexed color images

After RGB images, indexed color images are another way to display/work with colors in ImageJ.

Digital Image

Table of contents of Digital Image


In image processing softwares like ImageJ, what's a digital image? how the grays, colors are encoded? how these data are stored in a file?

Color images: RGB image

After the binary [Link] and gray-level images, the color images represent the last (and the most sophisticated) family of images used in image processing softwares. Colors are obtained by the combination of three primary colors. The latter may be different depending of the device displaying/printing the image.
In ImageJ, the most usual color images are encoded with the RGB color space.

Drawing a chessboard from a 2x2 unit cell

In my series Drawing a chessboard, a simple way to build the chessboard from a 2x2 unit cell.