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Author Topic: Yellow Blooming Canon 5D Question  (Read 14549 times)
dwdallam
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« on: January 03, 2007, 12:24:14 AM »
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What causes that ugly over saturated yellow "blooming" when shooting certain sunset pictures at certain exposures? It seems to get worse when shooting into the sunset itself, even after the sun as set.
« Last Edit: January 03, 2007, 12:24:49 AM by dwdallam » Logged

boku
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« Reply #1 on: January 03, 2007, 07:26:18 AM »
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White balance is required beyond the limits of adjustability. Like hitting a wall. That blocks the color up.
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Bob Kulon

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John Sheehy
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« Reply #2 on: January 03, 2007, 09:36:21 AM »
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What causes that ugly over saturated yellow "blooming" when shooting certain sunset pictures at certain exposures? It seems to get worse when shooting into the sunset itself, even after the sun as set.
[a href=\"index.php?act=findpost&pid=93413\"][{POST_SNAPBACK}][/a]

Can you link to a RAW file?
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dwdallam
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« Reply #3 on: January 06, 2007, 12:09:53 AM »
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Can you link to a RAW file?
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Yep, here you go:
[a href=\"http://www.dwdallam.com/shared/]http://www.dwdallam.com/shared/[/url]

I have my server in list mode for this directory. You'll see it when you get there.
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dwdallam
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« Reply #4 on: January 06, 2007, 12:10:47 AM »
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White balance is required beyond the limits of adjustability. Like hitting a wall. That blocks the color up.
[a href=\"index.php?act=findpost&pid=93450\"][{POST_SNAPBACK}][/a]

I've seen the same thing on film prints at shows. IS this also a film phenomenon, and I assume it is something we have to live with?
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John Sheehy
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« Reply #5 on: January 06, 2007, 10:56:31 AM »
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Yep, here you go:[a href=\"index.php?act=findpost&pid=94031\"][{POST_SNAPBACK}][/a]

Nothing is clipped in the RAW data.  The highlights look linear.  Perhaps it is your WB settings?  Your "as shot" setting is bad, and ACR's auto looks bad, too.  Daylight is what I would use as a starting point for this.
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dwdallam
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« Reply #6 on: January 07, 2007, 03:56:57 AM »
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Nothing is clipped in the RAW data.  The highlights look linear.  Perhaps it is your WB settings?  Your "as shot" setting is bad, and ACR's auto looks bad, too.  Daylight is what I would use as a starting point for this.
[a href=\"index.php?act=findpost&pid=94131\"][{POST_SNAPBACK}][/a]

I always play with the white balance. Could this be a damaged sensor?
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Jonathan Wienke
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« Reply #7 on: January 07, 2007, 07:26:56 AM »
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It's clipping. Setting the color temp to about 4400 minimizes it, but does not get rid of it at 0 EC. Given ACR's internal highlight recovery, if you show clipping at 0 EC, the RAW data is clipped, and other converters will block up the highlights with solid colors. Back off your exposure 1/3-2/3 of a stop, and the problem will go away.
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dwdallam
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« Reply #8 on: January 08, 2007, 03:41:55 AM »
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It's clipping. Setting the color temp to about 4400 minimizes it, but does not get rid of it at 0 EC. Given ACR's internal highlight recovery, if you show clipping at 0 EC, the RAW data is clipped, and other converters will block up the highlights with solid colors. Back off your exposure 1/3-2/3 of a stop, and the problem will go away.
[a href=\"index.php?act=findpost&pid=94291\"][{POST_SNAPBACK}][/a]


Jon,   I think this is the reason I was questioning the histogram conversation we had a while ago, that they don't lie when shooting RAW. I shot that with the camera histogram being a seemingly perfect gram, if my memory is faithful, and it got blown out.

I may be wrong here, if my memory fails me, but if you pop that into your 5D, what does the histogram tell you about it? If it tells you it's a pretty good exposure, then we have a problem. If I'm remembering correctly, then I need to adjsut something that affects the jpg histogram that is being read for the raw file?

Good to know nothing is wrong with my camera though.
« Last Edit: January 08, 2007, 03:43:20 AM by dwdallam » Logged

John Sheehy
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« Reply #9 on: January 08, 2007, 09:31:37 AM »
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I always play with the white balance. Could this be a damaged sensor?
[a href=\"index.php?act=findpost&pid=94275\"][{POST_SNAPBACK}][/a]

Play with the white balance where?

There is nothing wrong with your RAW image.
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John Sheehy
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« Reply #10 on: January 08, 2007, 09:35:14 AM »
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It's clipping. Setting the color temp to about 4400 minimizes it, but does not get rid of it at 0 EC. Given ACR's internal highlight recovery, if you show clipping at 0 EC, the RAW data is clipped, and other converters will block up the highlights with solid colors. Back off your exposure 1/3-2/3 of a stop, and the problem will go away.
[a href=\"index.php?act=findpost&pid=94291\"][{POST_SNAPBACK}][/a]

The RAW data isn't clipped, though.  Not a single clipped RAW pixel in the image.  This image shows up a weakness in RAW converters.
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John Sheehy
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« Reply #11 on: January 08, 2007, 09:38:32 AM »
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Play with the white balance where?

There is nothing wrong with your RAW image.
[a href=\"index.php?act=findpost&pid=94518\"][{POST_SNAPBACK}][/a]

Would you like me to post my manual conversion from the RAW?
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Jonathan Wienke
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« Reply #12 on: January 08, 2007, 06:23:37 PM »
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Jon,   I think this is the reason I was questioning the histogram conversation we had a while ago, that they don't lie when shooting RAW. I shot that with the camera histogram being a seemingly perfect gram, if my memory is faithful, and it got blown out.

I may be wrong here, if my memory fails me, but if you pop that into your 5D, what does the histogram tell you about it? If it tells you it's a pretty good exposure, then we have a problem. If I'm remembering correctly, then I need to adjsut something that affects the jpg histogram that is being read for the raw file?

Good to know nothing is wrong with my camera though.
[a href=\"index.php?act=findpost&pid=94475\"][{POST_SNAPBACK}][/a]

Your problem with my histogram-based exposure recommendation is that you obviously never bothered to do the testing I recommend to determint the exact relationship between what the histogram says and the RAW data. Once you nail down the exposure interval between histogram clipping and RAW clipping, and incorporate that into your exposure adjustments, shooting by histo works just fine, even when exposing to the right. You can't claim the method doesn't work when you're only doing half of it.
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dwdallam
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« Reply #13 on: January 08, 2007, 09:54:59 PM »
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Play with the white balance where?

There is nothing wrong with your RAW image.
[a href=\"index.php?act=findpost&pid=94518\"][{POST_SNAPBACK}][/a]

Play with it where--in ACR? You know, where is says "white balance," 'temperature," and "tint." I rarely change the WB in camera unless I know I'm going to be shooting in light I know doesn't change every 10 minutes--such as daylight without clouds, street lights at night, or strobes in a studio--which sunsets are not. In other words, if you need to adjust theWB a little after shooting, why do it twice, once in camera and once in your software?
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dwdallam
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« Reply #14 on: January 08, 2007, 09:58:09 PM »
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Your problem with my histogram-based exposure recommendation is that you obviously never bothered to do the testing I recommend to determint the exact relationship between what the histogram says and the RAW data. Once you nail down the exposure interval between histogram clipping and RAW clipping, and incorporate that into your exposure adjustments, shooting by histo works just fine, even when exposing to the right. You can't claim the method doesn't work when you're only doing half of it.
[a href=\"index.php?act=findpost&pid=94657\"][{POST_SNAPBACK}][/a]

No, you are quite right. I'm not saying it doesn't work though, just that, as you have stated, you must do some extra work to get it to work more accurately. I think a good starting point would probably be to turn the jpg contrast all the way down as low as it will go. I read that was a good practice somewhere.
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Jonathan Wienke
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« Reply #15 on: January 09, 2007, 01:21:07 AM »
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I think a good starting point would probably be to turn the jpg contrast all the way down as low as it will go. I read that was a good practice somewhere.

Probably on my site. But that still doesn't excuse you from doing the testing. If you can't be bothered to do it, you really don't have any right to complain when you have exposure difficulties.
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dwdallam
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« Reply #16 on: January 09, 2007, 03:26:15 AM »
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Probably on my site. But that still doesn't excuse you from doing the testing. If you can't be bothered to do it, you really don't have any right to complain when you have exposure difficulties.
[a href=\"index.php?act=findpost&pid=94720\"][{POST_SNAPBACK}][/a]

First, I'm not complaining. "Discussing" is not "complaining."

Second, just because I don't take your suggestions and apply them physically doesn't mean I don't learn by them.

Third, I had no idea exposure was directly linked to yellow blooming. So even if I had applied your information, I may still have gotten yellow blooming while bracketing, and we'd still be having this conversation.

Last, although you are extremely well versed in this technology and I greatly respect your time and knowledge, you over-extend that knowledge and diminish that respect when you tell me how and when I have a right to ask questions.
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Jonathan Wienke
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« Reply #17 on: January 09, 2007, 07:04:48 AM »
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First, I'm not complaining. "Discussing" is not "complaining."

Second, just because I don't take your suggestions and apply them physically doesn't mean I don't learn by them.

When you ask for the solution to an exposure problem after you've already been given a strategy for obtaining optimal exposure, it's hard to see how you learned from the original discussion about histograms and exposure we had. If you had applied the advice I gave you previously, you wouldn't have had any reason to start this thread.

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Last, although you are extremely well versed in this technology and I greatly respect your time and knowledge, you over-extend that knowledge and diminish that respect when you tell me how and when I have a right to ask questions.

If you want to be respected by people here and have them continue to take the time to answer your questions, you might want to start applying the advice you're given. Otherwise people will tend to regard answering your questions a waste of time and may stop doing so.
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John Sheehy
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« Reply #18 on: January 09, 2007, 07:29:23 AM »
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Third, I had no idea exposure was directly linked to yellow blooming. So even if I had applied your information, I may still have gotten yellow blooming while bracketing, and we'd still be having this conversation.
[a href=\"index.php?act=findpost&pid=94727\"][{POST_SNAPBACK}][/a]

There is no RAW exposure problem within the RAW you linked to.  Any less exposure would have resulted in a darker version of the same thing, with a lower signal-to-noise ratio.  Converters often boost the saturation of certain colors, causing clipping or near-clipping of one or two color channels in the output.  If its a highlight area, it can be even worse.  Perhaps you are seeing a combination effect of this fact, and the converter's inability to handle exposure to the right.

My simple manual, step-by-step conversion with IRIS has colors that look normal to me.  Should I post a small copy of it here?  When I get home, I will post a RAW histogram so you can see that it is not clipped.

I've never seen your render, or a precise description, so I don't know what is wrong with your conversion.  Your embedded JPEG is very pale, which is to be expected if you set contrast low and expose to the right.
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Jonathan Wienke
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« Reply #19 on: January 09, 2007, 03:29:00 PM »
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The RAW exhibits clipping when exposure is set to 0 EV in ACR. It can be gotten rid of by setting the exposure to about -.40EV, but that's using ACR's highlight recovery to deal with clipped RAW data. Not all RAW converters handle clipped highlights well; Canon's converter tends to output ugly blocks of solid, saturated colors under such circumstances, which is why I quit using it.
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