Adjust images with different gain

I need some help.

I have 32 images captured with a near infrared camera. The camera automatically adjusts the gain according to the signal intensity from the object being imaged. This means that two images with a similar mean signal intensity of the captured image in reality have very different intensities since the gain of one image is for example 2% of one image and 50% of another (I can read out the gain). Does ImageJ have a function to adjust this so all images can be scaled relative to each other according to the true signal intensity.


Hello Sorel -

Yes. Let me assume that your images are grayscale images,
and, for the sake of argument, 8-bit images.

Since (as I understand it) you know the gain used to acquire
each image, you can use
Process > Math > Multiply... (or Divide...)
to rescale each image according to its known gain.

However, to avoid overflowing or compressing your dynamic
range (presumably part of the reason your camera has
automatic gain adjustment in the first place), you should
convert your images to floating-point first:
Image > Type > 32-bit.

Thanks, mm


Thanks for your reply. I know the gain and accordingly i can do what you suggest. Also the conversion to 32-bit is wise, I was thinking to downscale instead of upscale the intensity to avoid saturation, but it would compromise the full range
for the images with highest gain.