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Matching a white balance between separate images?


mrwillvincent

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Hey guys, how's it going?

Am fairly competent within Photoshop but been utterly stuck with this task tonight. Working on a personal project and it's more frustrating than i'd anticipated. If any of you have got any suggestions they'd be much appreciated!

I'm basically trying to match the colour of the single jar shot to that of the jars in the colour reference file (the one with loads of jars), so it looks as if the single shot could be a closeup from the group shoot.

There's a batch of these single jar shots so I was looking for an adjustment I could do once and then apply uniformly to the rest.


My attempt was to create a series of adjustment layers that worked for one image and then apply that to the rest, but I couldn't come up with the correct combination of adjustments that matched the reference.


I'm confident with doing colour adjustments on the items inside the jar so you needn't worry about that, it's more the overall white balance / slight lessening of shadow underneath the shelves / shine of the glass jars / warmth and cleanliness of the picture's tone.


The single shots will cycle through as a GIF, so it's important to look as if it's just the content of the jars changing, rather than the entire shot - hence needing a single solution that was applicable to all pictures.

Hope this all makes sense, if you'd like a hi-res / psd file to tinker with just let me know.

Cheers! Will.

JarReference.jpeg
JarSingle.jpg
 
1. If, by any chance, you happen to have saved the single, currently unmatched images in RAW data format (ie, either *.nef or *.cr2) you would be able to get the very best match to the existing group. If you only saved the single shots as JPGs, we can still help you out. Pls. let us know.

2. Is the color balance consistent among all the currently un-matched photos, or will each require a separate color balance adjustment?

Tom
 
Hey Tom,

Unfortunately I've only got jpegs, the group shot is a psd file. My photographer did the bulk of the work on the group shot and gave me the psd to finish off.

Yes, the rest of the images are completely identical besides different contents in each jar / minute changes in the position of the jar.

Cheers, Will.
 
This is as close as I could get it. The shadows are giving me a hard time. I used a white balance technique (threshhold, curves, points) along with a B&C and a Photo filter (cool).

Tom, I would love to hear an explanation of the best way to do this in Photoshop.


JarSingle_01.png
 
Hey IamSam,

That's pretty close, there's a little bit of a greenish hue but well on the way to being there.

When you mentioned the use of Threshold and Points - what would the particular function of these tools be?
If by any chance you'd be able to take a screenshot of the various settings on these adjustments that'd be really useful for my learning.

Tom - I look forward to seeing what you come up with. If you require the full size jpegs / psd file just give me a shout and I can wetransfer it.

Many thanks,

Will.
 
To get the color in the ball park, my first step was to ingest your single jar image into ACR and use the WB eyedropper. I made no other changes in ACR. Next, I moved the image into PS. To reduce the remaining slight off-white color casts, I used the "White Neutralizer" module of NIK's Color Efx Pro package, but masked it away from the colored contents of the jar. The final step was using an "Exposure" adjustment layer to increase the overall brightness to try to match the reference image.

If you use the eyedropper tool to probe the colors in my tweaked image the neutrals are indeed very, very close to R=G=B except for the shadow under the platform where red is a couple of points high and blue a few points low.

IMHO, the main problem that remains is that in the individual jar image, there is strong shadowing under the platform, but there is much less shadowing in this area in the reference / group image.

If the shadowing is the same in all of the individual jar images, you can just develop a single dodge and burn correction layer (ie, gray tones painted onto a layer in "soft light" blend mode) to correct for it in all the single images. However, if the shadowing is different in each of the individual images, I don't see any automatic way to reduce it without also changing the contrast, texture, etc.

The other problem that I noticed (again, checked using the eyedropper tool) is that in the group (reference) image, there is a cast in the shadow area just below and to the right of the array of jars that is a slightly different color from the cast in shadow area in my tweaked image. This may or may not be significant to you, but it certainly is visible.

I hope this gives you another idea of how one might approach this problem.

T
 

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  • JarReference_with_1_tweaked_individual_jar-01_sRGB_698px_wide_8bpc.jpg
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Tom said:
To get the color in the ball park, my first step was to ingest your single jar image into ACR and use the WB eyedropper. I made no other changes in ACR.
Yes, I always forget about ACR!

I played with this all morning and still did not get very close. The ACR WB helped though.

I agree with you Tom, the problem is the strong shadowing under the platform. The lighting in the single jar photo is just too different.

Jars_01.png
 
Hey guys, cheers for your time on this, much appreciated.

Tom, I've been following your instructions through and am getting close(r), but nothing quite as good as the last image you posted.

Your instructions referenced a couple of processes completely new to me, I've got a few questions in response.

- Using the WB eyedropper in ACR. Clicking around the image gives slightly different results. Is there a particular point you're focusing on clicking here, or just the one that starts to make the shot resemble the reference?

- I've never encountered Color EFX Pro before, but have acquired a copy today and started to fiddle. With the white neutraliser I was wondering a few different things. Was there a specific colour you picked with the eye dropper? Did the other controls (Adjust Whole Image / Neutralise whites / Shadows / Highlights) play a significant role in your outcome?

- You mention the neutrals being close to R=G=B... what exactly does this mean in visual terms? I'm a handcrafter by trade, aspects of Photoshop more related to colour theory and photographer go over my head sometimes. I'd like to learn though!

The point about shadowing that you raised; the shadow under the platform is uniform throughout all single shots, but the shadows differ somewhat dependent on the content of the jars. As you suggested, I think I'll dodge / burn correct the shadows to an extent, but they don't have to match the reference completely. The focus of the images is the contents of the jars, and as long as the viewer doesn't instantly distinguish a difference between the single shots and that of the reference I'll be a happy man.

Many thanks for all your help, Will.
 
Hi Will - I'm glad you like the result. I will try to answer your questions, but unfortunately, I am not at my PS computer, so I can't see exactly what settings I used, but I'll do my best from memory. ...

- Using the WB eyedropper in ACR. Clicking around the image gives slightly different results. Is there a particular point you're focusing on clicking here, or just the one that starts to make the shot resemble the reference?
Here's where a bit of experience helps.

First, since I knew that I was going to be concerned with the colors of quite bright areas (eg, the wall, the lids on the jars, etc.), I didn't want to run into problems that often occur when RGB values are approaching 255,255,255. There are two ways one can help oneself: Make sure that ACR is set to output (a) 16 bit per channel (b) ProFoto images to Photoshop. So as not to interrupt the flow of this description, I won't go into why this helps, but it does. Also, since the brighter things in the scene (eg, the wall, the lids on the jars, etc.) were my focus, I decided not to brighten the "new" (individual) image until almost the very end of my color correction (CC) / white balance (WB) process. This is because one has more sensitivity to off whites in mid-tones than in highlights or nearly maxed-out areas of the image.

Second, from your description of how you will use the "new" (individual jar) images, it sounded like you were going to crop each reasonably close around the jar, and throw away all the blank wall in the image. So I wasn't distracted by color problems far from the jar, I cropped my one "new" image in this way.

Third, knowing that I needed to have accurate color, even though I have a good monitor (that I regularly calibrate with an external device), I decided not to rely on my monitor or my eyes, but rather, the next thing I did was to confirm numerically that the areas in the reference image that looked close to being pure white, actually were pure white. I did this so that I know I will be adjusting the "new" image to a pure white, not to some other color. To do this, I used the color sampler / readout tool and looked at the numerical values. When the red, green and blue values are all equal (ie, R=G=B), this means no color cast whatsoever - just a pure, colorless shadow, mid-tone, or highlight. Doing this probing was the point at which I discovered that the color balance on the reference image is wonderfully close to perfect except for a bit of a cast in the shadows below the samples, so my goal would be to balance the "new" individual jar image to pure white, not to some slight off-white color cast.

Fourth, with respect to using the WB eyedropper in ACR, I usually click around various points on the image, concentrating on areas that I feel are the most important *representative* areas to me, all the time mentally keeping track of the numerical values of the white balances that it suggests. For example, in this case, I probed things that I wanted to be white that were close to the jar, but only going slightly into the ( less representative) shadow areas.

- I've never encountered Color EFX Pro before, but have acquired a copy today and started to fiddle. With the white neutraliser I was wondering a few different things. Was there a specific colour you picked with the eye dropper? Did the other controls (Adjust Whole Image / Neutralise whites / Shadows / Highlights) play a significant role in your outcome?

The procedure I followed with the eyedropper in CEP's White Neutralizer module was almost exactly the same as what I did with the eyedropper in ACR -- I looked at a lot of areas and picked ones that I felt to be representative of my main color cast problem, ie, brighter areas such as the wall and the rim of the lid. The controls in that module make a huge difference in the success of the process. For example, the "shadow" and "highlight" sliders act differently in different modules of CEP. In this case, I let them stay at their default value of zero. Since I didn't want to take any color out of colored objects in the image, only out of things that were already nearly colorless, I put the "Neutralize Whites" slider quite high, maybe 80% (? - can't remember the exact value), but the "Adjust whole image" slider only around 25 or 30 %.

- You mention the neutrals being close to R=G=B... what exactly does this mean in visual terms? I'm a handcrafter by trade, aspects of Photoshop more related to colour theory and photographer go over my head sometimes. I'd like to learn though!

I already described what R=G=B means in an earlier paragraph, but let me add one comment here. You are doing very color-critical work, so you are exactly right in wanting to learn how to work "by the numbers". Sometimes relying on your eye and a good monitor is the best way to go, whereas in a case like this, working by the numbers is exactly what you should be doing.


The point about shadowing that you raised; the shadow under the platform is uniform throughout all single shots, but the shadows differ somewhat dependent on the content of the jars. As you suggested, I think I'll dodge / burn correct the shadows to an extent, but they don't have to match the reference completely. The focus of the images is the contents of the jars, and as long as the viewer doesn't instantly distinguish a difference between the single shots and that of the reference I'll be a happy man.

Unfortunately, I can almost guarantee you that the shadow discrepancy is significant enough that many viewers will notice it. I don't think the discrepancy in shadows between the individual jar images and the reference image has much to do with the content of each jar. Rather, I think it is occurring because the person who prepared the reference image somewhat reduced and smoothed out the shadows between the jars to give a nice visual effect. However, this hasn't been done to the individual jar images.

I don't know if you picked up on the suggestion I made in my previous email not to use the conventional dodge and burn tools on a real image layer, but to effectively do the same thing by painting lighter and darker grays on it's own layer set to "soft light" blending mode. There are many reasons to D&B this way in general (just Google the many descriptions of the advantages over the old D&B tools), but for your situation, it's particularly important and could save you a huge amount of time and offer consistency that would be otherwise impossible. Specifically, if the shadowing in the individual jar images is consistent (other than the small contribution of the contents of each jar), doing it this way allows you to simply bring a copy of that layer over each of the individual jar images and immediately get a very good correction with no further work.

If you have any more questions, don't hesitate to ask.

Best regards,

Tom
 
Arghhh - I knew that as soon as I hit "send", I would think of some other things to relay to you.

1. Nearly the your last step in the adjustment process should be to increase the brightness of the individual jar image to match the reference image. I prefer using an "Exposure" adjustment layer to do this, but almost any method that you are comfortable with will work.

2. Don't forget to save a copy of the above procedure exactly the way you have been working with it, ie, as a 16 bit per channel ProFoto file, but you should also make a separate copy and convert that into a conventional 8 bit per channel sRGB file for posting to the web, distributing by email, etc. I definitely would save this file, as well.

3. Now that I think of it, in the demo I posted, to get the purest WB, I may have applied the NIK CEP "White Neutralizer" module to the image twice, not just once.

4. The "White Neutralizer" algorithm does drain some color out of colored objects, even with the controls set the way I described and with a soft mask to exclude it from working on the contents of the jar, so I think I inverted that soft mask and used it to apply a vibrance/saturation enhancement to the contents of the jar to restore any lost color in the wood shavings.

HTH,

Tom
 
Wow Tom! That's a hell of a response, much appreciated. Can't work through in Photoshop right now but just to say thanks for your time and knowledge. I'll let you know how I get on over the weekend. Cheers! W
 
You are quite welcome, Will. It probably took 20x longer to type up the description than to actually do the work (especially since I was typing on the bouncy train ride home last night - LOL), so don't let the length of the response put you off. The problem is that without all the gory details, you would likely have a difficult time reproducing my approach and you would have no idea why I did things in particular ways when other approaches were possible.

Cheers,

T
 

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