Modify image colours in ColorSync Utility on Mac
You can use ColorSync Utility to modify an image file by adding effects, changing the colour space, resampling the image or correcting the colours and brightness.
Go to the ColorSync Utility app
on your Mac.Choose File > Open, then select an image file.
When the file opens, click the leftmost pop-up menu at the bottom of the window, then choose an option.
Match to Profile: Changes the colours in an image to match the ColorSync profile. ColorSync Utility modifies the pixels in the image to match the new colour model and ColorSync profile, then assigns the new ColorSync profile to it.
Assign Profile: Assigns the ColorSync profile for an image. ColorSync Utility does not modify the image saved in the file; it changes only the ColorSync profile for the image.
Apply Profile: Modifies the pixels in an image to match the new colour model and ColorSync profile, then assigns the image’s original ColorSync profile to it.
Click the middle pop-up menu at the bottom of the window, then choose the profile.
Click the rightmost pop-up menu at the bottom of the window, then choose the intent of the colour profile.
Automatic: Uses the default intent.
Perceptual: Applies realistic-looking colours, useful for photographs.
Relative Colorimetric: Maintains colour accuracy when specific colours are required, for example, in logos.
Saturation: Maintains the vividness of colours, useful for graphics such as pie charts and bar graphs.
Absolute: Adjusts the colours to account for the differences in white points.
Click Apply to save the changes to the file.
To adjust the colours and exposures in an image, click 
in the image’s toolbar. You can improve an image that’s too bright or dark, an image that doesn’t have enough contrast or an image that needs to be sharper.
To apply tone mapping to an OpenEXR image, click 
in the image’s toolbar. You can adjust the knee high, knee low, defog and exposure of a high dynamic range (HDR) image to the narrower range of a standard dynamic range (SDR) image.