How to use the command ppmcie (with examples)
The ppmcie command is used to draw a CIE color chart as a PPM image. The color chart is based on the CIE color system, and the command allows you to specify the color system to be used, the location of individual illuminants, and whether or not to dim the area outside the Maxwell triangle.
Use case 1: Draw a CIE color chart using the REC709 color system as a PPM image
Code:
ppmcie > path/to/output.ppm
Motivation: This use case is useful when you want to generate a CIE color chart using the REC709 color system. The REC709 color system is widely used in the broadcast industry and is the standard for HDTV.
Explanation: The command ppmcie is followed by the output file path, which is specified as > path/to/output.ppm. The output file format is PPM (.ppm), which is a binary file format used to store RGB images.
Example output: The command will generate a CIE color chart using the REC709 color system and save it as a PPM image at the specified output file path.
Use case 2: Specify the color system to be used
Code:
ppmcie -hdtv > path/to/output.ppm
Motivation: This use case allows you to choose the color system to be used for generating the CIE color chart. By specifying the -hdtv flag, the command will use the HDTV color system.
Explanation: The -hdtv flag is used to specify the color system to be used. In this example, the HDTV color system is chosen. The output file path is specified as > path/to/output.ppm.
Example output: The command will generate a CIE color chart using the HDTV color system and save it as a PPM image at the specified output file path.
Use case 3: Specify the location of the individual illuminants
Code:
ppmcie -red 0.4 0.3 > path/to/output.ppm
Motivation: This use case allows you to specify the location of the individual illuminants on the CIE color chart. By specifying the -red flag followed by the X and Y positions, you can customize the location of the red illuminant.
Explanation: The -red flag is used to specify the red illuminant, and the X and Y positions are provided as arguments. In this example, the red illuminant is placed at X = 0.4 and Y = 0.3. The output file path is specified as > path/to/output.ppm.
Example output: The command will generate a CIE color chart with a custom location for the red illuminant and save it as a PPM image at the specified output file path.
Use case 4: Do not dim the area outside the Maxwell triangle
Code:
ppmcie -full > path/to/output.ppm
Motivation: This use case allows you to generate a CIE color chart without dimming the area outside the Maxwell triangle. This can be useful when you want to visualize the full range of colors without any darkening.
Explanation: The -full flag is used to indicate that the area outside the Maxwell triangle should not be dimmed. The output file path is specified as > path/to/output.ppm.
Example output: The command will generate a CIE color chart without dimming the area outside the Maxwell triangle and save it as a PPM image at the specified output file path.
Conclusion:
The ppmcie command is a versatile tool for generating CIE color charts as PPM images. It provides options to choose the color system, customize the location of illuminants, and control the dimming of the area outside the Maxwell triangle. This command is particularly useful in the broadcast industry for creating color charts based on different color systems and illuminant configurations.
