RAW histograms from 30D - interesting combing patterns

Started Jun 28, 2006 | Discussions thread
OP Ruevs Forum Member • Posts: 69
Re: jrawio looks interesting

John Sheehy wrote:

Ruevs wrote:

I know of IRIS but it uses DCRAW to open RAW files - so no point.

IRIS does not use DCRAW's OUTPUT ; it only uses the decompression.
Having never seen any such gaps in any 20D or 30D RAW files, it is
quite possible that you will never see any in IRIS. If you do see
them in IRIS, then nothing can be concluded. If you don't, then
you can conclude that it is DCRAW's output code that is creating
the gaps.

Well in fact the gaps show up in Iris too. See this screen shot:

The only reason they are not visible initially is because the scale of the histogram is 0-65525, which compresses the graph too much. To replicate the above do the following:
1. Open IRIS.
2. "File ~ Load RAW file..."
3. Choose a CR2
4. "View ~ Histogram" - you see a "smooth" one at this point
5. Stretch the histogram window as wide as possible
6. In the histogram window choose "Options ~ Axes Setup"
7. For "Axe X" change the "Max" to 4095
8. Change "Tick spacing" to 512
9. Click "OK"

Now you see the "gaps" as in the screen shot above. Looks just like the result from my program:

except that I created RG1G2B histograms.

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