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Sunday, November 12. 2006
Apple Aperture: Hot Pixel Hell
I have been using Aperture lately for my digital photography post-processing. The work flow and smoothly working tools are addicting, but I have found a fatal flaw in its handling of RAW files. Aperture has no way of handling hot pixels. These dead pixels are a fact of life on digital cameras; although some cameras map these out for you from the factory, more will appear in time. Adobe, knowing this fact, built hot pixel removal into Adobe Camera RAW. Apple's algorithm, however, not only doesn't remove them, it enhances them into a bright dot, apparently falsely thinking the bright, out of place single pixel is image detail to be enhanced. This causes the single failed pixel to become a bright blob on your photo.
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| Aperture vs Lightroom at 100% crop showing the hot pixel location. |
There is a workaround for this; use the spot and patch tool on each image to mask out the dot. However, this is extremely time consuming, as depending on what is at that location on the image the dot may be unnoticeable, on a border forcing a manual patch adjustment, or the spot may be larger based on its surroundings changing Aperture's 'enhancement' of the dot, forcing an inspection of each image. It ends up changing your focus from 'I want this overall image to be the best it can be' to 'watch for the red dot.'
Until Apple fixes this issue, Aperture isn't going to be usable for most photographers unless they decide to work in jpeg (which masks this problem with compression artifacts), are lucky enough to have a camera that has not yet developed a hot pixel (but they will be in trouble when it does), or pre-process each photo with Adobe Camera RAW, then export to Aperture (losing the work flow advantages of Aperture; the whole point of the software).
Unfortunately I see no choice at this point but to use Adobe Lightroom for my photography needs, and hope Apple addresses this problem soon.
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I know some cameras will dynamically map out these pixels as they appear. Or so I understand from my research into the Canon Rebel XTi.
I wouldn't recommend counting on that too much:
http://www.dpchallenge.com/image.php?IMAGE_ID=398156
http://www.stevesforums.com/forums/view_topic.php?id=103573&forum_id=37
http://www.dpchallenge.com/image.php?IMAGE_ID=398156
http://www.stevesforums.com/forums/view_topic.php?id=103573&forum_id=37
It has been pointed out to me that Aperture has, in the RAW options, an 'Auto Noise Correction' check box. According to the Aperture documentation, this is supposed to fix this issue. However, in my testing, it made no difference whatsoever whether the check box is checked or not. I filed a bug report with Apple, but as they have no open bug system, there is no way to see if they are going to fix this 'feature'.
I found out a way to fix the hot pixels whit Aperture that are not all that time consuming.
(Tried to Trackback this entry without success.)
http://buglix.org/2006/12/28/hot-fix-in-aperture/
(Tried to Trackback this entry without success.)
http://buglix.org/2006/12/28/hot-fix-in-aperture/
This works well when the hot pixel is on a solid color with minimal detail. Unfortunately, as Aperture exaggerates the single bad pixel into an array of pixels, you have to use a 6-8 pixel patch to completely clear it up.
The spot and patch tool is not intelligent about edges, so you still have to check each picture and often make manual spot and patch adjustments. For example, people look very intensely at faces, and as it has a rather odd smoothing effect you get a 6-8 pixel facial blemish. To fix this, I find using the patch option from another piece of similar skin to be the best workaround.
Unfortunately this is all manual work. Copy and pasting a generic patch does indeed work well for some types of pictures. I can generally use it on most nature pictures without issues. I have found it to be particularly destructive on wedding pictures, where you have faces, clothing edges, and demanding customers that will notice facial blotches and frayed clothing edges.
The spot and patch tool is not intelligent about edges, so you still have to check each picture and often make manual spot and patch adjustments. For example, people look very intensely at faces, and as it has a rather odd smoothing effect you get a 6-8 pixel facial blemish. To fix this, I find using the patch option from another piece of similar skin to be the best workaround.
Unfortunately this is all manual work. Copy and pasting a generic patch does indeed work well for some types of pictures. I can generally use it on most nature pictures without issues. I have found it to be particularly destructive on wedding pictures, where you have faces, clothing edges, and demanding customers that will notice facial blotches and frayed clothing edges.
I see your point. I did not test on any portraits or similar images. I guess that it can look odd on any image with a large portion in the same color (i.e. like sky, skin etc).
Let's just hope that Apple fixes this in the next release (2.0?) of Aperture.
Let's just hope that Apple fixes this in the next release (2.0?) of Aperture.
Aperture 1.5.1 (last year) does not have this issue. At least it does for me. Up to ISO 3200 (EOS 5D and 1D Mk II and 1D), the "Auto Noise Compensation" effectively maps out both stuck and dead pixels.
Steven
Steven
Interesting; I've only been able to confirm the problem on the Canon 20D, where I'm still seeing the issue with Aperture 1.5.2 on OS 10.4.9. This may be a camera specific issue for that model or line.
Before I ordered Aperture I was researching about how it handled hot/dead/stuck pixels. My DSLR has developed a few nasty ones during the last year. During my research I came across this article “Apple Aperture Hot Pixel Hell” that states t...
Tracked: Dec 28, 17:20