I have a set of 3 jpg files with corresponding world files that I imported into GRASS using r.in.gdal. I did a d.rast -o for each of the 3 images and expanded my region with d.extend. Since the precision of d.extend isn't as good as the original region files (solved that problem yesterday), I manually changed the region to encompass the full extent of all 3 files. Then I did a r.patch on each rgb component (i.e. "r.patch input=image0.red,image1.red,image2.red output=map.red"), modified the cellhd file for map.red, map.green, and map.blue to have [0-rows] north/south and [0-cols] east/west with resolution values = 1. The image was completely clear as it should be when viewed in the GRASS X11 monitor (x0); however, using the PNG graphics driver produced an image that was slightly fuzzy (GRASS_WIDTH=cols and GRASS_HEIGHT=rows and GRASS_TRUECOLOR=TRUE), as if the driver was performing some operation on the image values before saving the file. I tried using r.out.tiff (not sure how to output an rgb as a tiff file, but I output map.red), and it also seemed fuzzy. I should also note that doing the same process to create a PNG file using just image0 and image1 worked fine without any noticeable fuzziness. What might be an explanation for this behavior? I have more images to add. Is the image quality going to degrade further? Is there anything I can do to produce a large (this one was 5610 x 2560) image that's as clear as GRASS will display in X11?
Thanks,
David