Rendering modes
The image can be rendered in multiple ways. For producing final image, the best results are achieved by interpolated or predictive for processes with regular color screen. The first produces smoother image while the second is better for enlargements by preserving more detail.
For processes with stochastic screen screen detection with relaxation is most useful.
Sometimes it is useful to render image in colors as seen in the scan. Then either original or interpolated original is good choice.
When working with gui, original, interpolated (for regular screen processes) and screen detection nearest (for stochastic screen processes) are most useful.
This mode passes data from the original scan to the output. It may correct geometrical errors and it can also turn original scan into HD data with scanner profile which can then be viewed in general image manipulation programs with HDR support. The output is either monochrome or color. For color scans the monochrome output is eitehr the infrared channel (if available and enabled) or simulated infrared channel based on channel mixing. Sharpenning is applied to monochrome data only.
scanner_red, scanner_green, scanner_blur parameters can be used to specify matrix profile representing scanner reaction to a given process.
This mode renders image in original color but performs demosaicing based on the knowledge of the color screen. This is useful when it is desired to reproduce the photograph as it appears physically but the output device is not capable of reproducing faithfully the color pattern.
Scanner profile can be applied.
This output mode works same way as original and interpolated original however it makes use of the matrix profile specified by profiled_red, profiled_green and profiled_blue which can be used to translate scanner's RGB data to estimated separations of the original process. Solver is available to determine this profile based on known spots of the scan.
Compares output of interpolated profiled original with the interpolated rendering. One makes use of the color profile while other takes into account the spartial information about the color screen. for quality scans, if the color screen is faded uniformly and if profiling is done correctly, the outputs should match.
Simulate digital screen on the top of the scan. This is faithful to the actual physical object, however not very practical in its digital form. Because scans are not sharp, realistic renderings are always somewhat desaturated and the regular pattern of the screen tends to interfere with digital processing
Use demosaicing algoirthm to eliminate the color noise.
Optional off-tree rendering algorithm
Normalize all colors to the same desnity. If scan is correctly analysed, this should make the photograph disappear and keep only the color screen
Shows result of analysis which is trying to classify every pixel to one of 4 categories (red, green, blue and unknown)
Try to perform demosaicing which works without knowledge of the screen (and can be applied to Autochrome, for example).