Changing image display between 4.10.x and 4.8.x using the same Window level and lookup table ?

I used 4.8.1 and started to use 4.10.1 recently. I found that they showed the same image in different gray levels.

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I have the same window level and lookup table settings. The data was loaded through PETDICOMextension. It seems that the value of the pixels is the same.

Just wondering what is different between 4.8.1 and 4.10.1 in displaying the image?

I don’t see any difference between the two images above.

For example, there are some black dots under the skin, maybe muscle. The bottom one (4.10.1) looks like less darker than the top one (4.8.1). Because the gray-scale represent the value of the pixels, it gives an impression that those pixels have different value, even though they are identical.

I agree with @lassoan that the effect is pretty subtle. @runze do you think these differences have clinical significance? Also do you have any way of knowing which one is more correct? (for example in comparison to a clinical system).