CODEWITHSUNDEEP
javapdfcolorsitext
Sam Barnum
Sam Barnum

Reputation: 10714

iText PDF colors are inconsistent in Acrobat

I'm generating a multipage PDF from Java using iText. Problem: the lines on my charts shift color between certain pages.

Here's a screenshot of the transition between pages:PDF Screenshot

This was taken from Adobe Reader. The lines are the correct color in OS X Preview.app.

In Reader the top is #73C352, the bottom is #35FF69. In Preview.app the line is #00FE7E.

Any thoughts on what could be causing this discrepancy? I saved the PDF from Preview.app and opened it in Adobe Reader, still has the colors off.

Here is the PDF that is having trouble. Open it in Adobe Reader and look at the transition between pages 11 & 12.

On checking this out further, it appears that the java.awt.print.PrinterJob is calling print() for each pageIndex twice. This might be a clue.

Upvotes: 2

Views: 971

Answers (2)

Mark Storer
Mark Storer

Reputation: 15868

Several different possibilities, yes.

  1. Different color matching. If you're using a "calibrated" color space on one page and a "device" color space on another, the same RGB/CMYK values can produce visually different values.

  2. If the graph is inside a Form XObject, the same graph can appear differently depending on the current graphic state when the form is drawn.

If you could post a link to your PDF, I could probably give you a specific answer.

Ouch. That PDF is painful to shclep through. I'd like to have some words with whoever wrote their PDF converter. Harsh ones. Lots of unnecessary clipping ("text" is being clipped hither and yon, page 7 for example), poor use of patters for images, but not using patters when it would actually help, drawing text as paths, and on and on...

EDIT: Which is precisely the sort of stuff you see when rendering Java UI via a PdfGraphics2D object. You CAN keep the text as text though. It's just a matter of how you create the PdfGraphics2D instance.

Okay, so the color of the line itself is identical. 0 1 0.4 RG. HOWEVER, there is some "transparency stuff" going on.

On pages that have images with soft masks or extended graphic states that change the transparency, the green line appears darker. On pages without, it appears brighter.

I suspect that all those other PDF viewers that draw the lines consistently don't support transparency at all, or only poorly.

Upvotes: 1

iPDFdev
iPDFdev

Reputation: 5834

The problem with the pages with darker colors is that they include a pattern object with a transparent image. When transparency is involved, Adobe Acrobat switches automatically to a custom CMYK profile and this causes the darker colors. Only Acrobat does this, other viewers behave just fine. The solution is either to remove the pattern object with the transparent image (it seems to be a drawing artifact of the PDF generator engine, it is not used anywhere on the page) or you can make the page part of a transparency group and specify the transparency group to use RGB colorspace.

Upvotes: 4

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