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Selected colour to dotted/dashed line
#1
Hi,

I need to convert a graph (and other similar ones) to B&W/grayscale. It's a typical line graph showing different plots with different colours (see attached). Converting to grayscale reduces the readability as the 5 lines become more or less indistinguishable. I cannot recreate the images in the analysis program with different line settings.

My idea was that I could make one line dark, one line light, one line dotted, one line dashed, and one line dot-dashed then convert. Other than laboriously doing it by hand (selecting the colour then using the eraser) with all the imperfections that will give, I can't think of any other way.

Any suggestions? What I need is a tool that replaces the selected colour with a dotted/dashed line.

Thanks for any help.

Mark


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#2
Since your graphs are just straight line segments, you could overlay them with path by just putting path anchors on the angle points (24 points per line). Then you would use Edit > Stroke path to stroke the lines, in Line mode when you can use various dot patterns (and even define your  own). You can also stroke the same path before hand in Tool mode with the erase to erase the existing line before restroking.

However... it would be about as fast and give a much cleaner result to use the Measure tool to measure the distance between each point and the X axis, enter that in a spreadsheet, apply a scaling factor, and recreate the curves with the dotted lines you want directly with the spreadsheet app.
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#3
(01-14-2023, 11:49 PM)Ofnuts Wrote: Since your graphs are just straight line segments, you could overlay them with path by just putting path anchors on the angle points (24 points per line). Then you would use Edit > Stroke path to stroke the lines, in Line mode when you can use various dot patterns (and even define your  own). You can also stroke the same path before hand in Tool mode with the erase to erase the existing line before restroking.

However... it would be about as fast and give a much cleaner result to use the Measure tool to measure the distance between each point and the X axis, enter that in a spreadsheet, apply a scaling factor, and recreate the curves with the dotted lines you want directly with the spreadsheet app.

Many thanks for the help. I found a different and very quick solution trying yours. For some reason 'Edit > Stroke path' was disabled for me. Perhaps because I had the colour selected. However, I tried 'Edit > Stroke selection' and, from there, I could very quickly chose a line style (dashed, dotted etc.) and fill that into the selection I had. For 5 lines, after a little experimentation, this was a work of about 1 minute or less per graph.


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#4
Edit > stroke path was disabled because you didn't use the Path tool Path but the Freehand SelectFree in polygon mode.
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#5
Converting to grayscale really makes the chart difficult to read.

Initially I thought of sorting by color and then applying strokes to each line (I think that's what you did).
In the copy I worked on, however, even when I tried to adjust the Threshold value, the selection had several interruptions in its continuity.

Creating paths seems to be a cleaner and easier option since it's just straight lines.

However, overlapping dotted lines does not give a good reading.
   

One option (maybe) is to just draw the lines with different thicknesses, and in just one of the 5 make a stroke (so as not to create a very thick line).
   

If there weren't so many overlaps between the graph lines, different dotted lines or even brushes created to customize the lines would be a good solution.

But definitely nothing like reading it on a colorful chart.
                               .....
Samj PortableGimp 2.10.28 - Win-10 /64.
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#6
Thanks for all the responses. If the publisher complains, I will definitely come back to some of the suggestions here. I like the different thicknesses idea.
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