I have a device with a blue LCD display where the backlight is blue and the letters are white. When I take photos of it with a cheap webcam, you cannot see any letter, because the blue light is too dominant. Does anybody have a cheap solution to this problem?

  • 1
    How much control do you have over exposure time/aperture etc? The 'simple' answer is to reduce the amount of light getting in… but that depends on the above. – Tetsujin Sep 26 '20 at 18:13
  • No, I don't have control over exposure time. Would it help to increase the ambient light. Flash light? – Harald Kneidinger Sep 26 '20 at 19:03
  • Try putting a red filter in front of your camera. Orange or yellow or anything that may significantly attenuate the blue. – user10216038 Sep 26 '20 at 21:18
  • @user10216038 The autoexposure routine would probably just increase exposure to compensate. It's going to try and expose the dominant brightness level as mid-tones. Filters only work when there are different colors that can be attenuated differently. – Michael C Sep 27 '20 at 2:38
  • @user10216038 you are right. It worked with both red and yellow cellophane. Sry I cannot upvote. – Harald Kneidinger Sep 27 '20 at 18:25

Mount a strong yellow filter, the display will image as black and the letters light yellow. If you can find some yellow cellophane X-mass wrapping ribbon or candy wrapping, you can experiment. If you like the effect, then buy a deep yellow photo grade filter. These were common in the black & white era. You can also buy a deep yellow gel filter. These are common in the theatrical stage lighting business. Likely if you look, you can find a piece of yellow flat glass or plastic to test this effect.


Readabilty issues on LCDs can often be tackled with polarizers without loosing the colour information. You could just hold some cheap polarizer, even a linear, between your webcam and the LCD. Try rotating it up to 90° to find the orientation with the effect you need.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.