timage
Author: Graeme Gill

## render/timage

### Summary

Create TIFF test image, suitable for evaluating various color transformations. By default a test image consisting of two hexagons and a grey wedge is produced. The two hexagons are the white and black corners of the RGB cube surface. This is useful in checking gamut mapping behaviour applied to an RGB colorspace.
An alternate rectangular "rainbow" representation of the surface of an RGB cube can also be created.
A third type is a set of stepped rectangles that explore the L*a*b* space, useful for testing profiles B2A tables (-p 6):

### Usage Summary

usage: timage [-options] outfile.tif
-v Verbose
-t Generate rectangular boundary test chart
-p steps Generate a colorspace step chart with L* steps^2
-r res Resolution in DPI (default 200)
-s Smooth blend
-x 16 bit output
-g prop Percentage towards grey (default 0%)
outfile.tif Profile to check against

### Usage Details and Discussion

The -v flag increases verbosity.
The default behaviour is to create the two hexagon plus grey wedge test image. If the -t flag is used, the alternate single rectangular surface test image is generated. If the -p steps parameter is given, than an L*a*b* test chart is generated.
The dots per inch of the image can be set using the -r parameter. Increasing this, increases the size and detail of the image.
Normally the images are generated using linear blending of the RGB values. If the -s flag is used, a smoother blending is employed. This is most desirable when generating the rectangular test image.
Normally an 8 bit per color component image is generated. If the -x flag is use, a 16 bit per color component image will be generated, giving smoother blends, particularly if a higher resolution (DPI) image is created.
The hexagon and surface test images are normally the surface colors of the RGB colorspace cube. If a percentage greater than 0% is given as an argument to the -g option, a test chart composed of colors away from the RGB cube surface, towards the center grey point will be generated. 100% will generate a completely grey image. Values of 10, 20 to 50% are more usual.
The L*a*b* step chart explores the range of L*a*b* values that are handled by an L*a*b* PCS B2A table, with the L* stepping from 0 to 100 in steps from the top left to the bottom right square, while the a* values range from -127 to 127 left to right in each square, and the b* values range from -127 to 127 bottom to top in each square.
The last argument on the command line is the name of the TIFF file to save the resulting image to.