ran2tiff(1) expose and convert a RADIANCE animation to TIFF frames


ran2tiff [ -W prev_frame_wt ][ -H histo ][ -D dir ] [ pcond opts ] [ ra_tiff opts ] frame1.hdr frame2.hdr ..


Ran2tiff takes an animated sequence of Radiance pictures and converts them by calling pcond(1) and ra_tiff(1) in such a way that exposure changes gradually from one frame to the next. It accomplishes this by computing a histogram for each image and blending it with a weighted histogram from the previous frame, where the weight is set by the -W option, or 0.9 by default. A value of 0.5 would mean that the previous frame carries 1/2 the weight of the current one, and the frame before that 1/4, 1/8 before that, and so on.

The -H option specifies a histogram file to be used to ensure continuous exposure between the current sequence and one before it. If the file does not exist, it will be created at the end of the conversion. If it does exist, its contents will be used as the histogram at the end of the previous sequence.

The -D option may be used to specify an output directory for the resulting TIFF frames. Otherwise, the current directory will be used. The output file names will correspond to the input names, but with a ".tif" suffix.

Ran2tiff also accepts the standard options for pcond and ra_tiff, though output to LogLuv TIFF formats is not supported. (There would be no point in adjusting the exposure if the output were HDR.) 


To convert a sequence of frames using a rapid human exposure response and LZW compression on the output:
ran2tiff -W 0.7 -h -z frame*.hdr

Similar to fieldcomb(1), this program works well with the "TRANSFER" facility of ranimate(1).


Greg Ward