Hello Michael, I figured it might be something like that but couldn't find any documentation online for it, thank you for the information! I'll look into HSB conversion, as well as the color inspection plugin as I am also planning on creating color profiles for the corals.
Best, Andre Briscoe PhD Student NSF CREST Center for Aquatic Chemistry and Environment Institute of Environment, an FIU Preeminent Program -----Original Message----- From: Michael Schmid <[email protected]> Sent: Wednesday, February 28, 2024 4:47 AM To: [email protected] Subject: Re: Histogram help Note: This message originated from outside the FIU Faculty/Staff email system. Hi Andre, for color images, the "standard" histogram display depends on the setting of Edit>Options>Conversions>Weighted RGB Conversions. If this option is on, the intensity on the x axis of the histogram plot is calculated as 0.299*R + 0.587*G + 0.114*B and labelled "Intensity (weighted)". If "Weighted RGB Conversions" is off, the intensity is calculated as (R + G + B)/3, and labelled "Intensity (unweighted)". In "R+G+B" mode, the histogram shown is the sum of the histogram of the histograms of the individual channels, i.e., the value for intensity 0 is the sum of the number of pixels where R=0 plus the number of pixels with G=0, plus the number of pixels with B=0. You will also see that the number 'N' of intensity values examined is three times as much as the number of pixels. If you want to examine bleaching, you are probably interested in color saturation, so you could convert the image to a HSB stack and look at the saturation and its histogram. There are also nice plugins for color inspection, e.g. the 3D Color Inspector/Color Histogram by Kai Uwe Barthel https://imagej.net/ij/plugins/color-inspector.html Of course, you have to make sure that illumination conditions and white balance of the camera are always the same. Accurate color measurements are a science on its own... Michael ________________________________________________________________ On 27.02.24 19:53, Andre Briscoe wrote: > Hello, > > I am currently working on designing a method to use ImageJ to estimate > bleaching in corals using the histogram function and was wondering what is > being represented in the R+G+B graph in case it is the graph best suited for > what I am trying to do. Does anyone happen to know? > > Best, > Andre Briscoe > PhD Student > NSF CREST Center for Aquatic Chemistry and Environment Institute of > Environment, an FIU Preeminent Program > -- ImageJ mailing list: http://imagej.nih.gov/ij/list.html -- ImageJ mailing list: http://imagej.nih.gov/ij/list.html
