IrfanView reported image size is half the correct value
Any suggestions on how to calculate the CAM_COLORMATRIX1 array.
Any suggestions on how to calculate the CAM_COLORMATRIX1 array.I've tried shooting a GretaMacBeth colorchecker card
A real Gretag Macbeth? Shot in daylight, at noon on a sunny day?Dave Coffin's dcraw contains code to compute the color matrix in this case. (It is not compiled by default; look for COLORCHECK in dcraw.c) Better yet, ask Dave to compute it. In which case, he will also include it in the next release of dcraw (an added benefit), with the rest of the pack to follow.
I'm saving as DNG and I noticed that the reverse_bytes_order function is really slow (and it's called twice). With 14MP to swap it takes a while. I looked at the code and noticed that the two lines:Code: [Select] mov r3, r4, lsr #8 // r3 = in >> 8 and r3, r3, r2 // r3 &= 0xFF00FFcould be replaced with:Code: [Select] and r3, r2, r4, lsr #8 // r3 = (in >> 8) & 0xFF00FF
mov r3, r4, lsr #8 // r3 = in >> 8 and r3, r3, r2 // r3 &= 0xFF00FF
and r3, r2, r4, lsr #8 // r3 = (in >> 8) & 0xFF00FF
I checked this in, it looks like it might save ~100ms on my d10. ~3.9s with new dng ~4 sec for old dng, ~3.1 for crw
One small optimization you could do is not reverse or patch the top and bottom border pixels. The side borders would probably not be a win for reversebytes, since it would get a lot more complex. Badpixel generation should probably skip all the border pixels, this would save time and memory.Interesting that write with uncached is different. What sort of differences are you seeing ? Doing it your way should be more correct in any case.
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