Hello,

I am using CorelDraw a lot for illustrations (together with epstopdf and pdflatex), but recently I noticed the following problem: The text in these illustrations looks "rasterized" when printed, but the surrounding "normal" text (created from pdflatex) does not. This seems to always happen when the text of the PDF is coming from CorelDraw, may it be exported as a PDF from within CorelDraw, printed to a PDF converter, or exported to EPS from CorelDraw, then converted via epstopdf, inserted in a Latex file, and processed with pdflatex to yield a PDF.

No, I am _not_ exporting the text as bitmap or curves or anything. Text and fonts are embedded into the PDF, and the text is infinitely zoomable and even selectable in Adobe Reader.

But if I choose "print text as bitmap" in my printer properties dialogue, all of the text (from CorelDraw as well as from Latex) looks rasterized, so I guess that the text that is coming from CorelDraw is rasterized in every case.

You might call me fussy, but this barely perceivable wobbling of the characters turns into ugly zigzag strokes if I print a booklet on coated paper with an 8 pt serifed font to fit all the lyrics on the 12x12 page.

Thanks for your help,

uwe

hi Uwe,

2 possibilities that come to mind:

1. text may appear rasterized if it not 100%K or exported with icc profiles. Perhaps your text is being converted to RGB black somewhere in the chain. On my rig, K 100  becomes R:28 G:28 B:26, then you see halftone dots on output. R0:G0:B0 is a solid black.

Try making some text in your project in RGB black with R0:G0:B0 settings - right beside your CMYK colors, and see how it comes out at your end.

2.  Any transparencies or other lens effects on the text? It may be rasterized at some point in your workflow...

Or, post a small CDR with a part of your project that is giving you trouble.

Thank you for the fast and rather accurate answer, Jeff! I conducted some tests in an attempt to find the weak link in my chain. The test document is very simple: nothing except 5 times the same text in optima 24 pt, with the following colors:

1. CMYK 0:0:0:100
2. RGB 0:0:0
3. Greyscale 20
4. Greyscale 10
5. Greyscale 0

Now obviously the 1st, 2nd and 5th should come out pin sharp, while the 3rd and 4th may be rasterized. I set up the color management of Corel for "professional output", and converted the document to PDF in the following ways:

1. Internal PDF export of Corel, ICC disabled, CMYK color model
2. Internal PDF export of Corel, ICC enabled, CMYK color model
3. Internal PDF export of Corel, ICC disabled, RGB color model
4. Printing to CutePdfWriter, ICC disabled
5. Printing to CutePdfWriter, ICC enabled
6. Exporting to EPS, ICC disabled, Linux epstopdf afterwards
7. Exporting to EPS, ICC enabled, Linux epstopdf afterwards

The ICC model enabled was the "generic offset printer" (not sure about the translation, "Auszugsdrucker" in german), perhaps this was not the best choice, as all printers I have access to are composite printers. Anyways, I printed on my small home b&w laser and on my office's bigger b&w laser.

My home printer did not rasterize anything. Even the 20% grey was pin sharp (in return it looked just as black as the other text). For the other printer, the results were diverse. I'll give the number 0 for "no rasterization at all", 1 for "very slight rasterization" and 2 for "obvious rasterization", thus 0,0,2,1,0 is about the expected result for the five colors of the test text. The results of the 7 variants described above were:

1. 2,2,2,2,2
2. 1,0,2,2,1
3. 0,0,1,1,0
4. 1,1,2,2,1
5. 2,1,2,2,1
6. 1,1,2,2,1
7. 1,0,2,2,1

So, the results are perfect for RGB export, and ok for my standard workchain EPS-epstopdf-latex if I format my text as RGB black and use ICC. At least for this printer. The one I want to print the CD covers on may be different, but I guess I'll just have to make some tests there, too.

Now, obviously you are right with your assumption that the text is rasterized because somewhere in the chain it is not completely black; and I suppose that it is inside the printer driver or the printer itself. Surely these color management problems are old hat for you guys, but I am not a professional... :)

Is there any further advice you can give me based on my test results? I thought about obtaining an ICC profile for the target printer to use during PDF export. Perhaps I could also inquire at the copyshop, but from last time I remember them being very friendly yet not proficient in those nit-picky technical details...

Thank you very much,

uwe

nixblik:

So, the results are perfect for RGB export, and ok for my standard workchain EPS-epstopdf-latex if I format my text as RGB black and use ICC. At least for this printer. The one I want to print the CD covers on may be different, but I guess I'll just have to make some tests there, too.

Yes, the end output device may be set up in ways you can't control. For ex, maybe shop has a Xerox digital laser with a PS driver, but they are using the PCL driver instead, which is unknown to you. FWIW, sending CMYK values down the chain to a pro device with a real PS driver should retain those values FME. If RGB conversions are introduced somewhere later after sending pure CMYK from the design file, this is where shifts can happen FME. I'll be the first to admit I don't have all the answers in this area. This is hard for me to admit - I strive to know almost everything else! LOL :-p

But from mad experiments to get my own projects to come out as expected, I've had to come at this from different angles.

nixblik:

Now, obviously you are right with your assumption that the text is rasterized because somewhere in the chain it is not completely black; and I suppose that it is inside the printer driver or the printer itself. Surely these color management problems are old hat for you guys, but I am not a professional... :)

"rasterized"  isn't the main issue. Here's why:

1. When people generally think of rasterizing, they think of bitmaps on their page at 300 DPI. This is a raster image. It's comprised of square pixels. Not dots.

But, in your case, the basic issue is that the text is being screened at perhaps 90% black because of conversions, so you are seeing the occasional artifact of that. There are 2 types of screening: FM and AM. We'll leave that for another day. :-)

2. Eventually, all data being printed is rasterized. This shocks many people.... but the purpose of a RIP (raster image processor) is to convert everything to output element data, including vector shapes and fonts. But, it happens with the output resolution set for the output device in the print driver for that unit. Most of the time, the value is set high by default, for ex, 2450 DPI on a Xerox DC-240 I work with. Otherwise setting to lesser amount doesn't use the equipment to it's greatest potential. Many small office laser printers output at 600 DPI. Many older color lasers also use 600 DPI, such as Xerox DC12.

The point: the vector artwork sent comes out sharp and clear because it being rasterized by the RIP at very high resolutions.

A fun thing to try for B/W Laser:

1.determine your laser printer's output resolution.

2. fill a page with paragraph text. print a copy.

3. Convert the text frame to a B/W 1bit bitmap, no dithering, at the resolution found in step 1. For my printer it was 600 DPI. Looks rough in Coreldraw, but print it.

The bitmap file blasted through system with surprising speed, since the driver doesn't need to re-calculate anything. You're giving the printer data on a 1:1 basis. Compare print to result from step 2. Same thing, eh?

 The point of this adventure? to show what a RIP is doing when you send it vector artwork.

nixblik:

Is there any further advice you can give me based on my test results? I thought about obtaining an ICC profile for the target printer to use during PDF export. Perhaps I could also inquire at the copyshop, but from last time I remember them being very friendly yet not proficient in those nit-picky technical details...

unless they are really curious, just conduct your own tests so you know what works for that equipment.