Blue Channel Limitations


Today’s Question: In “Evaluating Photos” you talk about the blue channel being the weakest channel. Is there anything I can do in camera to strengthen that?

Tim’s Quick Answer: Not really. Creating a good exposure, or even better an exposure that is as bright as possible without losing highlight details, will help ensure a relatively “strong” blue channel. But the blue channel in an RGB image will still generally be the “weakest” of the three channels in terms of overall quality.

More Detail: In general you will find that wavelengths of light that fall into the “green” range will generally be strongest in a photographic scene, with the “red” range typically being second. The “blue” range is generally the weakest. This is partly because more green and red light tends to be reflected in typical photographic scenes, and partly because image sensors (and the human visual system) are less responsive to blue light.

As a result, you’ll often find that the blue channel in an RGB (red, green, blue) image tends to be the weakest channel, with more noise and less overall detail than the other two channels. When the photograph was captured under relatively bright lighting conditions, the relative lack of quality in the blue channel won’t represent a serious problem. But when noise (and lack of detail) in an image is of particular concern, the blue channel is likely to be a significant contributor to the problem.

While there isn’t much you can do other than ensuring an optimal exposure, it is worth being aware of the potential for challenges with the blue channel, and to review all of the channels as noted in the “Evaluating Photos” course in the GreyLearning library.

If you’re not already a GreyLearning subscriber, you can sign up for the “Everything” bundle to gain access to the “Evaluating Photos” course as well as all of the other courses in the library. You can get more details here: