Simple image analysis problem

Dear forum,

I have a set of photographs where the brightness of color denotes the amount of given element. E.g. black = no gold at all & white = 100% gold and different grays in between.

Now, because i cant make out any trends by simply looking at my photos, i was wondering whether there was a way (e.g. ImageJ tool) which i could use to turn this brightness data to numbers.

Any ideas?

yours,
Jaakko

Hi Jaakko,

the good news is that this problem is already solved for you: your brightness data is numbers! If you open your image on ImageJ/Fiji, you can see the values in the place shown below:

Screenshot_2019-08-23_12-16-00

Hi, Eric, Thanks!! I have ImageJ and now I can see the value for any pixel. But how can i get these values from specified area, e.g. if i want to do small quadrats and get average values for those?

-Jaakko

You can draw regions of interest (ROIs) and press “M” (or go to Analyze -> Measure) - it will give you a window with measurements regarding your ROI. You can set which measurements you want to get by going to Analyze -> Set Measurements.

Great, excellent! I have multiple photographs and i would like to analyze exactly same ROIs for each photo (they are identical, just the element (e.g. gold) is different in each photo). So if there is easy way to do that, the info would be very helpful :))

thanks again Eric!!

-J

Hi Jaakko,

in that case, I suggest you look into Batch Processing and the macro recorder - with those tools, you should be able to generate a few commands that do what you want for each image (create ROI, measure, save results) and use those to batch-process your images. Your commands to be used in batch processing would probably look something like this:

title = getTitle();
makeRectangle(84, 73, 55, 50);
run("Measure");
saveAs("Results",title+".csv");
1 Like

Thanks alot! I try this, seems promising and realtively simple thing to do!
Have a nice week!!

-J

Hi @jaakkole,
If your ROI has a more complicated shape, you can also draw it on one image and then restore it on every image of your project (Edit>Selection>Restore Selection) or use

run("Restore Selection");

in a script

Nico

Hello and welcome,
If you just convert it into a text image, you will have all the data as a spreadsheet, which can be printed out if necessary.
Bob