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Need to Edit Out Colors from pdf Plots & Graphs: Which PhotoShop version will work best?

Need to Edit Out Colors from pdf Plots & Graphs: Which PhotoShop version will work best?

Need to Edit Out Colors from pdf Plots & Graphs: Which PhotoShop version will work best?

(OP)
I am in the middle of long research project requiring that I re-digitize a few (less than 30) old "paper-copy-scanned pdf files, and on-line pdf downloads, and on-line document and powe4rpoint files to "read" their graphs and plots.

I have a adequate software package that can digitize the graphs, providing they are in a bmp, png, or jpg format. Worse case, I can even "screen capture" the image into one of these "photo" versions, and use that.

However, several of the "most interesting" plots have very messy, very-much overlapping, very-many superimposed points. The software experts have given me some tips and methods that should work to do this manually (instead of the more frequent automatic curve following routines) but I will need to "edit" the images so that only the red points are "invisible or turned off: this way, the black lines and dots can be read. Then, I need to re-load the image, but only remove the black lines and dots so the red crosses and diamonds can be digitized. Repeat one more time for the blue crosses.

On occasion, I will also need to edit out (erase) the lines and marks as well, but I image just about such programs have an "eraser" function.

OK. This is a method, but what else are you going to do with papers written in the 1950's and 60's?

Which version of {Photoshop - or something else ?? - will do this type of editing on images?

RE: Need to Edit Out Colors from pdf Plots & Graphs: Which PhotoShop version will work best?

You can probably do it with Paint.net (free). Just use magic-wand tool to select the color you want to delete.
Alternately, you may be able to add a layer, set its color type to "multiply" and then paint it with RGB (0,0,255) (which will get rid of the red marks), leaving blue and...some of the black. You'd have to tinker with this method to get what you want.

Photoshop I believe has a "find and replace color" function as well.

RE: Need to Edit Out Colors from pdf Plots & Graphs: Which PhotoShop version will work best?

Gimp or PS should do the job, leverage the ability to use Layers in your favor. I would create a new Layer, then redraw what was required.

"Art without engineering is dreaming; Engineering without art is calculating."

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RE: Need to Edit Out Colors from pdf Plots & Graphs: Which PhotoShop version will work best?

If you're opening PDF files and when you're finished you would like to save them back in that same Adobe PDF format, I would look at using Adobe Illustrator. While Photoshop will open a PDF, it will convert it into something called a 'Photoshop PDF' and then when you save it that's what the format will be. Granted, it's pretty close, but not exactly the same thing. Illustrator is the best tool for editing/producing true Adobe PDF documents, at least that's my humble opinion.

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

RE: Need to Edit Out Colors from pdf Plots & Graphs: Which PhotoShop version will work best?

Every version of PhotoShop I've used (which is nearly all of them) has a "channels" feature. This feature puts each color onto its own channel. Then you can turn any channel on or off to create a series of images with just the colors you want without having to erase anything. From within PhotoShop you can save these images as any of the image formats (.jpg, .bmp, .png, etc) or you can print to a regular .pdf file (saving to .pdf creates the compatibility problems that JohnRBaker mentions).

David Simpson, PE
MuleShoe Engineering

"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.
The plural of anecdote is not "data"

RE: Need to Edit Out Colors from pdf Plots & Graphs: Which PhotoShop version will work best?

Most CAD programs have the ability to insert a graphic.

Do than, then draw points over the points on the graph, then collect the coordinates of those points.

RE: Need to Edit Out Colors from pdf Plots & Graphs: Which PhotoShop version will work best?

You can even use MS Paint to strip a color, by selecting the right foreground and background colors and right-clikc-dragging the eraser tool.

RE: Need to Edit Out Colors from pdf Plots & Graphs: Which PhotoShop version will work best?

(OP)
My (well-belated!) thanks to all who have contributed.

RE: Need to Edit Out Colors from pdf Plots & Graphs: Which PhotoShop version will work best?

What was your final solution?

"Art without engineering is dreaming; Engineering without art is calculating."

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RE: Need to Edit Out Colors from pdf Plots & Graphs: Which PhotoShop version will work best?

Phrasing?

RE: Need to Edit Out Colors from pdf Plots & Graphs: Which PhotoShop version will work best?

(OP)


Quote (Madmango)


What was your final solution?

Two files are attached below showing the problem of overlapping data points.

Based on the recommendations above - and, again, thanks to all for the analysis - I used Hypersnap graphic markup and editing software to replace the colors with "white" pixels. What surprised me was finding that the "actual color" I thought I was looking at was not "red" or "blue" or even "black". rather, what looked like "red" was softer mix of the three basic colors mixed together. And, at different places, the three were mixed differently for some reason.

Thus, I could not just replace 255 + 0 + 0 with "white" but rather needed a four-step process:
245 + 10 + 10 -> find and replace,
235 + 20 + 20 -> find and replace
225 + 30 + 30 -> find and replace
215 + 40 + 40 ... The Hypersnap program did have a ""tolerance" band for each operation, and I selected the maximum tolerances possible at each step.

It was more difficult than I'd of liked however.

RE: Need to Edit Out Colors from pdf Plots & Graphs: Which PhotoShop version will work best?

(OP)
And, results after "removing" the "red" so the "blue" diffuse radiation data points were left visible.

Notice that the colored red "labels" also got replaced with white pixels along with the unwanted data points, but there were always spare pixels left behind each time, which required simple "erase" secondary processing.

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