Help please - Shadow issues with 350D

[AussieBloke]

I went to process some photos I took from a trip to Amsterdam recently, and when I look in the shadow areas on a lot of my pictures I see some dreadful artefacts - namely colour noise and posterization. I went back and looked at some other pitcures that I have taken recently, and they show similar issues. I think this may be an issue with the camera (maybe the image processor?), but what do you guys think? I've attached one example with a 100% crop, shot in RAW with EF-S 17-85mm IS lens, ISO 200, f6.3, 1/160. Shot in Adobe RGB, converted in Camera RAW. Then coversted to 8-bit and sRGB and saved to JPG. No other post-processing has been done. These artefacts also appear at the sensor's native ISO 100 sensitivity from what I have seen.

Any help is most appreciated.

Thanks,
Sean

[Ronnoco]

Some of your problems revolve around the original lighting. You are shooting from the shade into a bright sky with some very dark areas toward the shoreline. The result is too much contrast and some weak colour at least in how these shots display on this site.
Your original shooting would have been better with a graduated neutral density filter with the dark part toward the sky or a polarizing filter.

After the fact, you need the right software and a familiarity with it. Part of it is selectively brightening certain areas to bring out colour and detail in either Photoshop or PaintShop Pro X and reducing artifacts and other problems with these as well or better still with plug-ins.

Ronnoco

[another view]

Shot in Adobe RGB, converted in Camera RAW. Then coversted to 8-bit and sRGB and saved to JPG. No other post-processing has been done.

Couple of comments. I've heard (no personal experience) that Nikon cameras seem to work better with Nikon's Capture software for conversion, than with Adobe Camera Raw. I have a Fuji and ACR works very well, but I don't know about Canon. Try using Canon's RAW converter and see if you get an improvement. Also, if you're not doing any other post processing than what's listed (including levels, curves, etc) then it seems like you're doing a lot of extra work without getting any benefit from it, other than changing the white balance during RAW conversion. 16-bit RAW files can have a lot of advantages to them for post processing but if you're not using them that way, maybe try shooting jpeg. RAW isn't necessarily any better than jpeg in 100% of situations.

[AussieBloke]

Couple of comments. I've heard (no personal experience) that Nikon cameras seem to work better with Nikon's Capture software for conversion, than with Adobe Camera Raw. I have a Fuji and ACR works very well, but I don't know about Canon. Try using Canon's RAW converter and see if you get an improvement..

I did some quick tests, using Zoombrowser, and also shooting Jpeg and I still get a similar amount of noise/posterization. I guess what I need to know is whether I should be expecting these kinds of artefacts, especially in the darker parts of an image. I spoke to a friend last night who owns a 30D, and he said that he saw a similar thing in underexposed areas of his images.

Also, if you're not doing any other post processing than what's listed (including levels, curves, etc) then it seems like you're doing a lot of extra work without getting any benefit from it, other than changing the white balance during RAW conversion. 16-bit RAW files can have a lot of advantages to them for post processing but if you're not using them that way, maybe try shooting jpeg. RAW isn't necessarily any better than jpeg in 100% of situations.

I think there has been a misunderstanding - I put that info in, just to emphasise that the artefacts were not caused by my post-processing. In reality I often do a lot of work on my pictures and find RAW capture invaluable for the 'leg-room' that it provides. I wouldn't shoot any other way!

[Frans]

I have had this problem as well. The way I tend to reduce the noise in the darker regions is shoot the image a F stop or so higher than what is required from the normal light settings. Then adjusting the level using UFraw (free raw converter for most formats)back to where they should be. This ensures that the dark areas are out of the noise area of the sensor. This method does have problems when the dynamic range of the image exceeds 6 F stops (limit of the sensor as well as UFraw).

Photo that have noise in the dark areas can be fixed by reducing the detail only the dark area, then sharpening it up again. I use “The Gimp” to do this task. You will find it will make quite a difference. Try the following:
filter -> blur ->Selective Gausian Blur , Blur radius 10, Max delta 10
filter -> enhancements -> unshapen mask, 0.1 pixel, 100% sharpen threshold 7

Gimp is free and can be down loaded from the web. I assume you can do the same with PhotoShop.

Best of luck
Frans