White Balance and Colour Correction

[nukie]

Taken from the other thread which seemed to get really off topic.

white balance

Shooting in RAW mode eliminates that problem

how so? RAW just means that there is no compression. The white balance is the equivilent to filters or film that is balanced for different types of light.

I can't remember where I read it, but I'm quite sure that saving a photo in RAW mode lets you play with the histogram before saving it as a jpg or tif. I've not got around to playing with it on my G5 yet, so don't ask me how to do it. But yeah, it *should* work.

This is the only mention of it I could find.

Yeah... you are talking about the levels. You can always do that in photoshop to get a true white even if you did have compression.

How are the levels different to the White Balance? I always thought they were the same thing if not similar.

And I know that its possible to alter the levels of any photo to get a "more correct" white. But once its a jpg, you're working on pixels with loss in them. With RAW mode, the idea is that its uncompressed, and you fiddle with the whtie balance/levels/histogram before it gets saved as another file format.

Well, at least thats my understanding of it.

 

[voodoocat]

I think we are on the same page.

I was responding to the comment that RAW eliminated the need for white balance. That is true to an extent, but you can still edit a jpg the same way. Yes, there is a loss in quality due to the compression, but the differences are minimal.

 

[nukie]

So to a point, if I shoot in RAW mode, then I can not care about the white balance in the camera (shooting constantly in a middle'ish range). Then correct the colour when its downloaded to my computer?

Granted I can do this when saving as a JPG, but with the RAW mode I shouldn't lose any clarity, and gain an ideal white balance.

Just seems as though there has to be a catch.

 

[voodoocat]

Well there may be more to it than just the histogram. You may need to do a little work to the colors using curves or hue/saturation. Don't take my word for it though. I have little knowledge of digital sensors.

Now the Sigma SD9 does not have any compression yet it still has white balance.

 

[nukie]

Hmmmmm. Just had a quick play with my g5, and it lets you select RAW Mode and chagne the white balance as well. So it must do something.

I think its time to head off to google. If I find something which sheds more light on the matter, I'll post it in here.

 

[voodoocat]

I was reading through the manual for my slide scanner. At the end there is a section with information on getting the the right colors.

Knowing the complementary colors is very important in color balancing. If the image has a specific color cast, either subtracting the color or adding its complementary color will create a natural looking image.

If the image is too:

Red - Decrease the amount of red
Green - Decrease the amount of green
Blue - Decrease the amount of blue
Cyan - Increase the amount of red
Magenta - Increase the amount of green
Yellow - Increase the amount of blue

 

[Dew]

with that graph u presented voodoo .. it sounds like selective color in photoshop? ... im always taking yellow out of my photos with that one

 

[voodoocat]

In this situation I am talking about the curves.

I will be uploading a tutorial soon..

 

[drlynn]

Yep, Dew. It can be done with Selective color as well as with the Curves tool. To me, it seems to be a matter of preference, though the Curves tool is more powerful, letting you limit the modification to only the midtones, or highlights, etc.