Plotting Color Intensity Evolution in Image Stack

I have a stack of images (from a video) in which I want to track the evolution of the intensity of a particular color (blue in this case) across the stack, to give me a plot of color intensity vs time (see sample data here:

I know how to select ROIs and then use Multi Measure to get the gray scale intensity evolution. However, this is not suitable as it picks up too much noise from other colours.

Perhaps a solution would be to first convert the images so that everything non-blue (or not of the colour of interest) is white, and the shades of blue only remain? But I am not sure how to do this.

Good day,

could you please be more specific with what your problem really is.

What makes slecting the regions of blue color so difficult?
Perhaps different color system may help.

How do you want to track what exactly?
Is there are single compact region of blue color per frame?
Why do you think you need ROIs?

What noise do you mean and why from other colors if you are looking for blue?
Is it a specific kind of blue that differs from the blue RGB channel?



Hi Herbie,

My apologies for being unclear.

Please see sample data here:

I may not need ROIs at all. In my head, I would like to simply analyse each entire image for intensity of the colour blue, but I don’t know to do this.

Thanks for your help, I really appreciate it.

Well, or actually not very well.

In any case you will have to use an appropriate color space for this task. There are serveral options. Have a look at the built in tool (Image > Type > …) as well as at the plugins Color Space Converter, Color Transformer and Colour Deconvolution on the plugins list.

plot of color intensity vs time

So you mean just the sum of that color intensity taken over the whole image for every image in the stack. The question is: What do you really mean by “color intensity”, saturation, brightness…

Your example image stacks suffer from illumination and thus color changes that make the task more difficult.

Good luck