Image editing to change colored lines to a black and white pattern

March 8, 2009 7:51 AM

I have a line graph with the lines in color. I want to reprint it in a black and white publication. What's the fastest and easiest way to edit the lines in the graph to change them from color to a readable black and white pattern (e.g. dots, dashes).

Here is the color image: http://dshort.com/charts/bears/four-bears-large.gif

So for example, I would like to replace the blue line labelled "current bear" with a black and white patterned line of (e.g.) dots.

The one clumsy way I could think of is to sample the blue color and change it to black then use an eraser tool to break up the black line into a pattern. Ugh.

posted by storybored to computers & internet (7 comments total)

What software did you use to make the graph?
posted by Houstonian at 7:59 AM on March 8

The fact that it's a GIF file is going to make it more difficult than it needs to be. I would guess that the person who originally created the graph created it in a vector graphics format (Adobe Illustrator, PDF, SVG, or something along those lines), and such a file would be a lot easier to manipulate in the way you're asking. You might try contacting them and asking if they have any vector graphics versions of the graph.

And of course, you've already been in touch with the creator to get permission to reprint the graph, so you've already got their contact information. Right?
posted by Johnny Assay at 8:04 AM on March 8

The one clumsy way I could think of is to sample the blue color and change it to black then use an eraser tool to break up the black line into a pattern. Ugh.

Unless you can get ahold of the original plot or remake it with your own tools, this may be your only option, I'm afraid.
posted by Blazecock Pileon at 8:26 AM on March 8

It seems like it should be easy, but I just tried it with irfanview and it didn't work like I thought.

(Well, it was able to convert it to grayscale nicely, so if that will work for your publication, good on ya. But pure black and white not so much- it dropped all the light grays to white.)

Maybe a more advanced program like photoshop would be able to selectively replace colors- just replace anything that's not white with black.

Actually, being a gif might make this easier- just edit the color palette to make every color black, except for white and that cream background color in the callouts, and make it white. Tried this in irfanview and it worked, but was kinda ugly.

But uh, yeah, talk to the author. They can probably rerender the graph using black and white, and adjust the line gauges to display the data more nicely.

Or, the base info is fairly easy to get, just make your own graph might be easier?
posted by gjc at 8:31 AM on March 8

Unless you can get ahold of the original plot or remake it with your own tools, this may be your only option, I'm afraid.

It's easy

1) Create a small image that you want to use as a pattern fill
2) In photoshop, go to Edit | Define pattern and create a pattern.
3) In your picture, go to Select | Color range and click on the blue bar. (use the slider to give a high sensitivity so you don't get annoying fringes due to anti-aliasing)
4) Create a new layer
5) Press create layer mask, it will automatically have your selection as the mask
6) go to Edit | Patern fill to fill the new layer with your pattern, already blocked out with an appropriate layer mask

I also used an eraser to get rid of of the slight blue border that still existed, and added a drop shadow to make it easier to see where the border was.

The picture is pretty ugly too, you'll have to play around with different patterns to make it look good. A dot pattern might look better then the checkerboard one I used. There's no way to get a dashed line that follows the actual direction of the graph line that I know of.
posted by delmoi at 9:33 AM on March 8 [2 favorites]

Data Thief may help you out....

Then you can make your own......now that I think about it, I am not sure how well it works with line data that is that complicated
posted by rvrlvr at 11:30 AM on March 8 [1 favorite]

Thanks Delmoi, that looks promising!

Johnny Assay: I've got permissions already, natch.
posted by storybored at 1:21 PM on March 8