To investigate further could you please provide the following information.
Input file(s)
Screenshots showing the input, and clearly indicating what you expect to get instead, and also clearly indicating the application/browser being used to view.
Are you attempting to change the colour of a specific object, annotation, or background in the PDF?
The image above is a mock-up of a part of the application screen I want to develop.
When customers order a book print, we edit the PDF file and print it.
The image above is the objects want to edit and its color values.
These objects will be selected by the mock-up Image >> Select Objects By CMYK Color Range.
Cyon: 0 to 0
Magenta: 0 to 100
Yellow : 0 ~ 0
Black : 0 ~ 0
The image above is the result of changing the value selected in Mockup Screen >> Change CMYK Color. (results I want)
Depending on the magenta ink density, the color value can be the same and the opacity can also be adjusted.
For another example, if i want to keep all other values the same and subtract only the black color ink value,
Cyon: checked Keep
Magenta: checked Keep
Yellow: checked Keep
Black : 0
The UI may change
Anyway, After selecting objects through the CMYK Range setting in that way,
I want to change it by specifying the color and opacity