jpeg in PowerCADD goes bad?

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jpeg in PowerCADD goes bad?

Postby pbacot » Tue Nov 18, 2014 1:39 pm

I put some color jpeg images in PowerCADD so I could compose a sheet. I printed a pdf and all was fine.

Later (a day or so) I came back to the PC file and some of the jpeg images looked worse. In particular white spots appeared here and there (not a general covering, just groups of very coarse bright white in specific areas). I had to reimport the images to get another good pdf output. This isn't a large file.

What's going on? Some other good application to do this in (combine pdf and jpeg to make a sheet to print to scale)? I could probably use LayOut but the pdf output is always too large byte-wise.
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Re: jpeg in PowerCADD goes bad?

Postby huc » Tue Nov 18, 2014 5:53 pm

The issue sounds the same as one I reported almost one year ago (6 Nov 2013)

The problem is specific to raster files (I tested PSD, JPG, and PNG compressed/uncompressed) and pixels with a value of R1 G1 B1 becoming transparent after a file is saved/closed and opened. Because they become transparent they appear as white dots/noise only because the drawing page is white.

That R1G1B1 value is 'almost' or 'virtually' black (R0G0B0 = pure black) -- check your image in photoshop or other edit application and I'll wager the problem is in areas that are very dark (shadows, dark colors, etc)

Going from memory - I recall two easy fixes:
1) draw a black box and put it behind the jpg images.
2) print/export the original image to PDF, then place the PDF

I never got around to writing up a formal caddpower.com article as the process was pretty detailed in isolating the problem and I just never felt compelled to invest the time to address the subject in the level of detailed needed.

Again check the image in Photoshop and measure the pixel value of the suspect pixels. I created a basic test file that recreated the problem with the exact pixel values after testing about 100 different sample points in a file exhibiting the problem -- but it would be good to know if it affects other pixel values as well

Hope that helps.
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Re: jpeg in PowerCADD goes bad?

Postby pbacot » Tue Nov 18, 2014 7:18 pm

Thanks, Brian! That sounds about right. It was a couple renderings and not much done to adjust colors, so there's probably some very black spots in there. I didn't know jpeg could be transparent, but of course the interaction of the software is beyond me anyway. Good to know, It's not that bad a problem with the fixes. At first I was a little shocked (about to send to printers) to see the errors because I had spent a lot of time studying the pictures, and couldn't believe I had left it like that. I'll see if I can test it. Thanks again for the help!
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Re: jpeg in PowerCADD goes bad?

Postby huc » Wed Nov 19, 2014 2:02 am

You're correct JPEG doesn't support transparency

But remember PCD does some digital slight of hand with respect to bit maps when they're in a drawing - in particular when the Alpha channel feature was added [edit: to the program]. Point being what came in as a JPEG can get tweaked and colors knocked among other things -- therefore it's no longer like the original JPEG placed.
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Re: jpeg in PowerCADD goes bad?

Postby Rob C » Mon Sep 26, 2016 6:12 pm

Bump an old topic:

This is still an annoying problem. I like using PowerCADD to assemble images like a page layout program, and everyone is doing this more and more for presentations. Can anything else be done?

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