White Balancing errors

[ray_parkhurst]

I often do white balancing with a "true grey" sticker that has 2 tonalities of grey. If I focus on the sticker, I can check each tonality to make sure they are close to equal RGB. I don't know the actual ratio of the values, so can't calibrate that. I do have a Pico Target which is awaiting evaluation, but it is not ideal since the surface of the paint is not as uniform in color as I'd like.

To mitigate non-uniformity, I will often "defocus" the true grey surface to minimize color variations. This works great for apochromatic or at least well-corrected lenses, but can cause color shifts with lenses with large LoCA. With good lenses, this gives me the best WB.

Yet, since I use DPP, which has a WB "eyedropper", I still see variations in WB versus eyedropper application. I recently tried the Olympus Workspace program, which has a manual WB adjustment. I found it to be quite slow, but also quite accurate.

What process do others use for white balancing?

[rjlittlefield]

I set white balance by matching peaks in the histogram, using the upper limit sliders of a Photoshop "Levels..." adjustment layer.

If I'm particularly well organized, I'll do this with a separate gray target image, then apply the same adjustment to other images shot with the same setup.

But more commonly, I'll apply that same adjustment technique based on some neutral background area in my real images, restricting the histogram to that particular area through use of a selection marquee.

Matching peaks in the histogram is quite robust against variations in brightness across the reference area, because the RGB curves will all have the same shape after matching.

--Rik

[ray_parkhurst]

I set white balance by matching peaks in the histogram, using the upper limit sliders of a Photoshop "Levels..." adjustment layer.

If I'm particularly well organized, I'll do this with a separate gray target image, then apply the same adjustment to other images shot with the same setup.

But more commonly, I'll apply that same adjustment technique based on some neutral background area in my real images, restricting the histogram to that particular area through use of a selection marquee.

Matching peaks in the histogram is quite robust against variations in brightness across the reference area, because the RGB curves will all have the same shape after matching.

--Rik

I can rarely do WB on actual images, since few have anything close to neutral grey in them. For some coin images, especially graded coins from NGC or ANACS, the surrounding plastic is a nice white, and indeed folks who view the images expect it to appear "white". Thus even if these areas are a bit off in color, using them to do white balance is almost a necessity to produce images which are accepted as color-correct.

Occasionally I will shoot a coin on a background of the two-tone true grey mentioned above. This gives an excellent reference to maintain proper color balance through post-processing. I find this especially useful for toned coins, where the background reference gives "proof" that the coins are represented with their true colors.

[kds315*]

I set white balance by matching peaks in the histogram, using the upper limit sliders of a Photoshop "Levels..." adjustment layer.

If I'm particularly well organized, I'll do this with a separate gray target image, then apply the same adjustment to other images shot with the same setup.

But more commonly, I'll apply that same adjustment technique based on some neutral background area in my real images, restricting the histogram to that particular area through use of a selection marquee.

Matching peaks in the histogram is quite robust against variations in brightness across the reference area, because the RGB curves will all have the same shape after matching.

--Rik

I can rarely do WB on actual images, since few have anything close to neutral grey in them. For some coin images, especially graded coins from NGC or ANACS, the surrounding plastic is a nice white, and indeed folks who view the images expect it to appear "white". Thus even if these areas are a bit off in color, using them to do white balance is almost a necessity to produce images which are accepted as color-correct.

Occasionally I will shoot a coin on a background of the two-tone true grey mentioned above. This gives an excellent reference to maintain proper color balance through post-processing. I find this especially useful for toned coins, where the background reference gives "proof" that the coins are represented with their true colors.

Try SPECTRALON (R) gray targets excellent but expensive. Virgin white Teflon (PTFE) also works well.

https://photographyoftheinvisibleworld. ... lon-r.html

[viktor j nilsson]

Try SPECTRALON (R) gray targets excellent but expensive. Virgin white Teflon (PTFE) also works well.

White teflon (PTFE) seems like a great suggestion for us on a budget. It made me think of that roll of plumber's tape I use to seal the sight tube of my espresso machine. A quick search revealed this:

https://petapixel.com/2018/09/08/plumbe ... ce-photos/

I will definitely try that out.