How to adjust colors and tones using a grayscale chart?

[Guest]

Hello.
I have a question regarding photo editing in Photoshop. I have photos of some product (only .jpg files, not RAW). There is a grayscale chart visible in the corner. Both of the pics were taken with a flashlight, but white balance was set differently (for training purposes): one to a flashlight, the other one to tungsten/incandescent.

How can I use this grayscale chart to adjust colors and tones of the photo? I thought I should use curves (or levels) adjustment layer and by using black, gray and white eyedropper tools, sample in a black, gray and white color from a grayscale chart and by that, set accordingly black, gray and white point of the image. The problem is that this approach gives unnatural colors and rather odd look of the product.
I will appreciate any help. Regards

[TheDigitalDog]

Couple of ways to do this. 

You might want to use Adobe Camera Raw as a filter, WB using its WB tool (eyedropper) on the white patch. Even if you get a neutral from that patch, you may still want to adjust to taste, using the Tint/Temp sliders. 

[Nancy OShea]

Go to Filter > Camera Raw Filter in the top menu bar. When you open an image in ACR, the white balance adjustment is near the top, called Temperature. Adjust sliders as needed. It’s easier to adjust white balance of RAW photos, TIFFs, PSDs, and other minimally-compressed files. If you adjust a JPEG too far, you might notice color artifacts later.

Photoshop Curves Adjustment - Automatic Option

1. Add a Curves adjustment layer.
2. Click on right hamburger menu of the Properties tab (see screenshot).
   
   
3. Select Auto Options.
4. Select the “Find Light & Dark Colors” option. Click Ok.
   

Related links:

https://photographylife.com/how-to-correct-white-balance-photoshop

https://www.adobe.com/creativecloud/photography/discover/white-balance.html