Canon PowerShot G2 –
RAW format info.
My
sample-gallery has lots of my G2 photos in it.
Project
status (april 2003) – Having another look after almost a
year away from it :-(
I don't expect to get very far before I
have to do real work again. Sharpening is to next thing to look
at.
In May 2002, I started work on rolling my one canon RAW format converter - the primary aim was a to write a hot-pixel remover for the G2. But I got carried away – six week later I still haven't removed that pixel (which is trivial to do) because I've been trying to improve the picture quality instead. I've had some success but the improvement if any has been small. Because the images on these pages have to be fairly large files in order to have adequate quality I've spread them over several pages.
Page 1, Is about decoding the raw format and shows what the CCD data looks like with and without the bayer matrix colors superimposed - and shows the result of applying a simple linear interpolation to fill in the missing color values.
Page 2, Is about my attempt to improve the quality on the green image by using various averaging routines which try to avoid averaging across edges. These methods have be abandoned but are included for completeness.
Page3,
I extracted the color information and combined it with the
"improved" green image from page 2. I built edge maps
and attempted to write a smarter color averaging routine using
this edge information. This was mostly successful.
Page4,
Some
bugs were fixed and I'm definitely getting sharper images - but I
also get worse artifacts along edges. I wrote a routine to seek
out some of the artifacts and reduce them. It improves things a
little but could be better. I did some minimal color and gamma
correction but no saturation control yet. I'm giving the image
enhancement a rest. I still have things to try but completing the
basic processing is more important. I may do more on artifact
removal and play with adaptive sharpening. Note that there has
been no sharpening filter applied.
Page
5, Now in mid June I'm doing more on the color management. My
program is just becoming usable. Once I finish the color controls
can I mostly eliminate post processing in photoshop. In my
opinion the less times a image is re-edited the better. Fixing
the image at conversion time is better than trying to fix it
later.
April
2003.
Want to play? Some files are here.
