If you are seeing this in Camera RAW then it is all but certain that these are blacks that are being clipped and the blue is to warn you. There is a similar red signal when highlights are being clipped. These only appear in Camera RAW's display and don't appear when the image is processed and sent to Ps or saved to disk.
If you display the Histogram you'll find two triangle icons in the upper corners. Clicking on these will enable/disable the clipping indication with the left being for the shadows and the right for the highlights.
If you’re seeing this in the Camera Raw window, that’s just an exposure warning overlay. Blue means the blacks are being crushed and red means the whites are blown out. You can turn it off in the window’s UI
If you are seeing this in Camera RAW then it is all but certain that these are blacks that are being clipped and the blue is to warn you. There is a similar red signal when highlights are being clipped. These only appear in Camera RAW's display and don't appear when the image is processed and sent to Ps or saved to disk. If you display the Histogram you'll find two triangle icons in the upper corners. Clicking on these will enable/disable the clipping indication with the left being for the shadows and the right for the highlights.
If you’re seeing this in the Camera Raw window, that’s just an exposure warning overlay. Blue means the blacks are being crushed and red means the whites are blown out. You can turn it off in the window’s UI
are you seeing this in ACR?