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07-27-2009, 09:09 AM   #1
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White balance - does it affect RAW?

Hi, not too sure about this, but everyone keeps talking about how they set their white balance... I only ever shoot in RAW and I read that white balance doesn't affect RAW images, only JPEG.

So other than the three parameters (shutter, ISO, and aperture), is there much else I can place with in terms of digital settings on my camera for RAW images?

Thanks - just need help on the clarification of this

07-27-2009, 09:26 AM   #2
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WB setting when shooting raw are changeable later in post processing. WB settings in jpeg are fixed. The way that I like to think of it is a two step process to displaying a raw image. The raw image just is. Either the camera or the computer reads the raw image, then references the settings like WB, sharpness, saturation, etc. to determine how to display the image. Any of those settings can be changed later, because it's only a guideline, not set in stone.

In a jpeg, all those settings actually affect the pixels that are recorded and you can't go back and change them later (to the same degree.)

Does that make sense to you, or only in my own rambling mind?
07-27-2009, 09:37 AM   #3
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QuoteOriginally posted by code4code5 Quote
WB setting when shooting raw are changeable later in post processing. WB settings in jpeg are fixed. The way that I like to think of it is a two step process to displaying a raw image. The raw image just is. Either the camera or the computer reads the raw image, then references the settings like WB, sharpness, saturation, etc. to determine how to display the image. Any of those settings can be changed later, because it's only a guideline, not set in stone.

In a jpeg, all those settings actually affect the pixels that are recorded and you can't go back and change them later (to the same degree.)

Does that make sense to you, or only in my own rambling mind?
Makes sense, just want to be sure that no adjustment in WB while taking raw images will actually change the look of the image... sorry for repeating myself, but is that what you're trying to say?

Plus I make minor changes in iphoto afterwards anyway
07-27-2009, 11:11 AM   #4
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Raw Images

All the camera settings, such as WB, Sharpness, etc., are recorded in the .PEF of .DNG file, along with the raw image, itself. The raw image is basically not much more than the data, straight from the sensor.

When a raw image is displayed, those settings are used to interpret the image and create a displayable image for the screen or printing. However, the settings are not part of the image. They are only applied when the image is displayed. That is why they are so easy to change. The camera or software simply re-interprets the raw image, using the new settings, without making a change to the image itself.

By contrast (no pun intended), those settings are used by the camera, or computer software, to transform the raw image into a jpeg. In the process, the raw image data is discarded and only the jpeg image data is left. The jpeg contains the "sum" of the raw image data and the camera settings. It is much harder to change these settings in a jpeg, for this reason. The original data from the sensor is lost.

When post-processing a raw image, even then, the raw image is usually not changed. The changes are stored in a seperate file, using something called eXtended Markup Language, or XML. Every time you open the raw file (.PEF), the software re-applies the previous changes that are in the XML file. If you shoot in .DNG (Adobe's Digital NeGative), the XML is stored in the .DNG file, but is not applied to the raw image. Again, it is only applied when the file is opened.

07-27-2009, 11:54 AM   #5
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Hmmm that makes sense - I'm guessing that's why when you edit an image (.pef) in iphoto, your pic shows up but you can always decide to reset it back to the original.

So you're saying that even if i take a pic in RAW only on my k200d and adjust the WB, that a difference will show up on the camera screen, but later on I can access the unedited RAW?

Thanks and sorry for the noobishness
07-27-2009, 01:31 PM   #6
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I read a technical discussion a few years ago about this. If I understood and remember correctly, the conclusion was that under most conditions, white balance is just a number attached to the image later. However, the white balance setting can affect exposure, and exposure can affect whether some channels are overexposed to the point where they clip. Using auto white balance works most of the time. Under extreme conditions, you can get better results setting a custom WB. I have tried this when I use an infrared filter and it helps.
07-27-2009, 02:50 PM   #7
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I don't know whether or not WB setting affects exposure directly but it does affect the way the image appears on the review LCD which is an argument in favor of getting it 'in the ball park' in-camera. Normally the default for RAW processing later is also 'as shot' so getting it right in-camera would generally be preferable to having to change it later.

The other question would be how important is color accuracy? For some types of photography (like landscape?), it is acceptable to just get it to 'look right'. In others (like product photography) accuracy may count more so a manual white balance, or perhaps shooting a known quantity like a color checker chart, or both might be advisable.
07-27-2009, 04:23 PM   #8
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QuoteOriginally posted by Just1MoreDave Quote
I read a technical discussion a few years ago about this. If I understood and remember correctly, the conclusion was that under most conditions, white balance is just a number attached to the image later. However, the white balance setting can affect exposure, and exposure can affect whether some channels are overexposed to the point where they clip. Using auto white balance works most of the time. Under extreme conditions, you can get better results setting a custom WB. I have tried this when I use an infrared filter and it helps.
I assume you're speaking of when shooting only in RAW?

07-27-2009, 05:06 PM   #9
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QuoteOriginally posted by Just1MoreDave Quote
I read a technical discussion a few years ago about this. If I understood and remember correctly, the conclusion was that under most conditions, white balance is just a number attached to the image later. However, the white balance setting can affect exposure, and exposure can affect whether some channels are overexposed to the point where they clip. Using auto white balance works most of the time. Under extreme conditions, you can get better results setting a custom WB. I have tried this when I use an infrared filter and it helps.
Essentially that's correct. I don't know if it was the same discussion, but I was involved in one similar regarding infrared. It was not so technical in nature but rather some real world tests were done. It was concluded that doing a custom WB did have an affect on what you could achieve afterward when doing the PP, and I read some of the other more scientific and technical discussions on this and do believe it is linked to how the channels ended up clipping in such situations.
07-27-2009, 07:58 PM   #10
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QuoteOriginally posted by esman7 Quote
I assume you're speaking of when shooting only in RAW?
Yes, and with my comparatively low-tech *ist DS. If you have a camera with better AWB or histograms for each channel, the camera might do a better job even in extreme conditions.

If you have Adobe Camera RAW and a RAW image, you can see the clipping I'm talking about. Open an image, click the Highlights box to show them, set the exposure up until some highlights are clipping, then adjust the WB slider.

I nearly always shoot RAW, and adjust white balance later. I sometimes like to see what the "wrong" WB setting looks like, maybe keeping a bit of yellow from incandescent light, for example.
07-27-2009, 09:07 PM   #11
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QuoteOriginally posted by khardur Quote
Essentially that's correct. I don't know if it was the same discussion, but I was involved in one similar regarding infrared. It was not so technical in nature but rather some real world tests were done. It was concluded that doing a custom WB did have an affect on what you could achieve afterward when doing the PP, and I read some of the other more scientific and technical discussions on this and do believe it is linked to how the channels ended up clipping in such situations.
I recall similar discussions on dpreview, where it was proven that *some* camera do *slightly* alter the RAw data according to the selected WB, so that getting the WB "right" in camera would reduce the likelihood of clipping. But emphasis on the word "slight" here - it's not like JPEG were the WB is completely "cooked" into the image. It's more like, hmm, the difference between actually cooking chicken soup versus maybe briefly dipping a piece of cooked chicken into a pot of water and imparting a slight chicken flavor to what is still essentially just a pot of water.

Anyhow, as I recall, it as only certain 6MP models that did this; none of the more recent cameras do.

Last edited by Marc Sabatella; 07-27-2009 at 09:12 PM.
07-28-2009, 08:46 PM   #12
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That would certainly jive with my experience with the K100d and the K20d. I find that the K100d was harder to edit for WB while the K20d seems more willing to be flexible in PP.
07-29-2009, 05:31 AM   #13
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Hi esman7,

Do you always use iPhoto to edit your RAW files?
I think iPhoto always processes the DNG file before displaying it on the screen. I noticed this because the image looks different when I revert to original, but only for a second because iPhoto processes it again automatically.
I had a red dot in a few images that iPhoto was fixing so that's how I noticed this. I haven't googled this yet, but does anyone else know what I'm talking about?

Anyway, I'm pretty sure iPhoto applies your in-camera settings for WB as well before displaying you the photo, but I can only speak for the DNG files because I own a Samsung.
And yeah, Samsung doesn't know that Windows isn't the only OS...
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