7D Maze/low ISO artifacts UPDATE

Started Oct 25, 2009 | Discussions thread
ejmartin Veteran Member • Posts: 6,274
Re: OK. I did that and this is what I get

Here is the difference of the two channels (CFA split using IRIS, difference viewed in ImageJ), the selection is on the cyan patch of your RAW:

The lower left white patch on the CC chart shows this in its difference:

The vertical streaking is a cause of interpolation artifacts, as is an overall shift of means which is most predominant in cyans and yellows. While the cyan patch #18 has a difference in means of -18 in G2-G1, the yellow patch #16 on the CC chart shows a difference in means of +38 for G2-G1. I believe this is statistically significant, even though it is several times smaller than the std devs of the patches, since the white lower left patch has a much higher std dev but a much smaller mean difference. So either the CFA is misaligned on your camera, or indeed as some have suggested Canon has decided to use a four-color CFA, with the two greens having somewhat different spectral responses. I hope to find the time to dig into this latter possibility later, by looking at whether the spectral responses of your CC chart agree with those of bronxbomber's copy, and the test images at IR.

-- hide signature --
Post (hide subjects) Posted by
tko
Keyboard shortcuts:
FForum PPrevious NNext WNext unread UUpvote SSubscribe RReply QQuote BBookmark MMy threads
Color scheme? Blue / Yellow