Make sure the file names of your images contain information on which fluorescence channel they were obtained in (e.g. “001_dapi.tif, 001_gfp.tif, 002_dapi.tif, 002_gfp.tif”, etc. You could also place them in seperate folders (one “dapi” and one “gfp” folder).
Select the files/folders, drag&drop them into your “Images” module.
The NamesAndTypes module needs information on how to identify different channels. So if you added “dapi” and “gfp” to your filenames, you could try this
Press the update button below (its not visible in the image), and see what happens. If you get an error, make sure all above is true.
That should solve your error message (and if you get an “Zero Length Selections not Allowed” error, it will still work).
However, the rest of the pipeline would depend on your images. As GFAP is extranuclear (?), you will need to identify the cell bodies to determine if the cell is positive or not. I think you could try the “Human cytoplasm-nucleus assay (SBS Vitra)” example pipeline to measure the cell body intensities. Alternatively you could identify the nuclei and expand them a little with the “ExpandOrShrinkObjects” module, and measure the resulting object.
Trial and error, don’t be discouraged!