Value Of RGB At A Pixel(x,y) In Image J Home » Color Picker Imagej » Value Of RGB At A Pixel(x,y) In Image J Maybe your like Color Picker Ui Design Color Picker Ui Ux Color Pixel Art 4j.com Color Pixel Art Classic Y8 Color Pl098 Valentine Value of RGB at a pixel(x,y) in image J Image Analysis analyze-particles, imagej Sandra_Mankore (SANDRA M P) June 7, 2021, 7:26am 1 Hi, I have a doubt in image J I have some x and y position of few pixels in my ROI manager and I have to find and store corresponding RGB value.I didnt see any tool to collect RGB of a pixel Interesting fact: While you scroll through the image in fiji/image J RGB value is showing under toolbar.But I dont know how to store these. Please help… Getting started with ImageJ1 macros phaub (Peter Haub) June 7, 2021, 4:05pm 2 Hi @Sandra_Mankore check https://imagej.nih.gov/ij/developer/macro/functions.html getPixel(x, y) Returns the raw value of the pixel at (x,y). Uses bilinear interpolation if 'x' or 'y' are not integers. Use getValue(x,y) to get calibrated pixel values from 8 and 16 bit images and intensity values from RGB images. Note that pixels in RGB images contain red, green and blue components that need to be extracted using shifting and masking. See the Color Picker Tool macro for an example that shows how to do this. https://imagej.nih.gov/ij/macros/tools/ColorPickerTool.txt 2 Likes Sandra_Mankore (SANDRA M P) June 10, 2021, 5:42am 3 Sir, What do mean by ‘shifting and masking’ to get RGB from RGB images? Can you explain with an example? phaub (Peter Haub) June 10, 2021, 6:53am 4 RGB images are stored as Integer data. Integer data consists of 32bits - or in other words - contains 4 Bytes (4 x 8bit = 32bit). Integer = Byte3 | Byte2 | Byte1 | Byte0 The 8bit R, G, B values are stored as Byte2, Byte1, Byte0 in the Integer value. To retrieve the 8bit R, G, B values from the Integer number the data bits have to be shifted by the shift operator >> and masked by the hex number 0xff. The operations can be seen in the above ColorPickerTool macro (mentioned above): macro "Color Picker Tool -C44f-o4499" { getCursorLoc(x, y, z, flags); v = getPixel(x,y); row = nResults; setResult("X", row, x); setResult("Y", row, y); if (nSlices>1) setResult("Z", row, z); if (bitDepth==24) { red = (v>>16)&0xff; // extract red byte (bits 23-17) green = (v>>8)&0xff; // extract green byte (bits 15-8) blue = v&0xff; // extract blue byte (bits 7-0) setResult("Red", row, red); setResult("Green", row, green); setResult("Blue", row, blue); } else setResult("Value", row, v); updateResults; } Here is a simple version: v = getPixel(x,y); red = (v>>16)&0xff; // extract red byte (bits 23-17) green = (v>>8)&0xff; // extract green byte (bits 15-8) blue = v&0xff; // extract blue byte (bits 7-0) Sandra_Mankore (SANDRA M P) June 10, 2021, 6:41pm 5 Sir, We have coordinates of ‘centre of mass’ different particlesin ROI manager. Can you please share the macro to get each XM,YM from Results box directly and take their RGB value. Result box481×512 45.8 KB phaub (Peter Haub) June 11, 2021, 5:40am 6 Sandra_Mankore: Can you please share the macro If I would have such a macro I would share it with you. But I don’t have it. My hint: Create a macro with the following steps Collect the x/y pairs from the result table Iterate through all pairs Retrieve the pixel value by using getPixel(x, y) for each x/y pair Extract the RGB values as described above Regarding macro programming a lot of information can be found: https://imagej.nih.gov/ij/developer/macro/macros.html https://imagej.nih.gov/ij/developer/macro/functions.html https://imagej.nih.gov/ij/macros/examples/ Hope that helps. gabriel June 11, 2021, 9:27am 7 Note that the centre of mass of a region does not necessarily fall in a pixel belonging to that region unless there are some other conditions fulfilled (eg the region is convex, contains no holes, has certain size [where is the centre of mass in a region made by 2 pixels joined by the corners?], etc.). The pixel XM, YM could actually be on the background (eg a “C” shaped region) or even in a different region that occupies that background pixel. Sandra_Mankore (SANDRA M P) June 11, 2021, 10:27am 8 Yes sir…I am aware of that…Lucky thing is that all my particles are round in nature…nothing convex… Sandra_Mankore (SANDRA M P) June 11, 2021, 10:28am 9 Sure sir…The links and macro code helped.I was able to write code for collecting RGB value for specific x and y. If possible,can you please tell how to collect xm and ym , and itirate the macro multiple times?? phaub (Peter Haub) June 11, 2021, 1:19pm 10 Check Built-in Macro Functions There you can find the command to retrieve the values from the ResultsTable getResult("Column", row) Returns a measurement from the ImageJ results table or NaN if the specified column is not found. The first argument specifies a column in the table. It must be a "Results" window column label, such as "Area", "Mean" or "Circ.". The second argument specifies the row, where 0<=row<nResults. nResults is a predefined variable that contains the current measurement count. (Actually, it's a built-in function with the "()" optional.) Omit the second argument and the row defaults to nResults-1 (the last row in the results table). See also: nResults, setResult, isNaN, getResultLabel. Please check the macro examples to learn how to iterate over the array of results. phaub (Peter Haub) June 11, 2021, 1:24pm 11 Looping over ROI results table and extracting XY coordinate values Image Analysis Hi all, Sorry if this questions is a little basic, but I’ve had not had much luck searching the forums or macro examples for a specific answer to my problem. As a follow up to my last post, I’ve been trying to figure out the best way to iterate over multipoint ROIs in multiple stacks, before extracting the XY values for each point. I’m still learning the macro language and this is what I have with so far: numROIs = roiManager("count"); for(i=0; i<numROIs;i++) // loop through ROIs { roiManag… phaub (Peter Haub) June 11, 2021, 1:25pm 12 Results Table Analysis Image Analysis Hi @v.82588, there are methods for reading / writing tables: getResult and setResult. You can see them and read their documentation by typing “Result” in Fijis script editor: [image] The saveAs method allows you to save a table to disc. Furthermore, feel free to read a bit more about working with tables on slides 12-17 here: I hope that helps! Cheers, Robert Sandra_Mankore (SANDRA M P) June 11, 2021, 5:00pm 13 Thank you sir…This helped… 1 Like Related topics Topic Replies Views Activity Value of RGB at a pixel(x,y) in a polygon selection of an image Image Analysis imagej 4 183 October 30, 2023 Calculate RGB values for all the particules Image Analysis imagej 18 7653 March 1, 2021 How do we get the rgb values using image j? 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