I got a magazine back from the printer. It contained some low-res bitmaps that were supposed to be hight res, and they are in the .cdr file. One image is a masked bitmap object that is grouped together with  an ellipse (that has a text wrap property set to it) and then a drop shadow applied to it. The bitmap is 360 ppi in the cdr file but looks very grainy in print. A check in the pdf file confirms that the image is 100 ppi, see attached.

I also checked and the rendering resolution in Options/Workspace/General was set to 100 ppi for the reason of previous web work.

So, does this setting of drop shadow resolution affect even the bitmap that it's linked to? Yes, it's obviously it does, but is that as designed or a bug?

(I know I should have run the preflight bitmap check in Acrobat, but I'm no expert on Acrobat and found out of that function only now when I looked for it. I will certainly do it in the future.)

Sure you didn't have a wrong setting in the PDF export which I assume you used.

For print it should be either Acrobat 4 or one of the PDF/X settings.

Render I set to 600. It doesn't matter for the web as you can set resolution at the last minute.

It does sound like the shadow and bitmap got combined into a single object and that object would likely be rendered at the resolution of the item with the lowest ppi.

Lars you likely need to do a test. Maybe using a 600ppi bitmap and a 72ppi res for the shadow so it's really obvious what is happening.

Yani:

Sure you didn't have a wrong setting in the PDF export which I assume you used.

Yes, I didn't have a downsampling active whatsoever.

Yani:

For print it should be either Acrobat 4 or one of the PDF/X settings.

Yes, I used PDF/X-3

Yani:

Render I set to 600. It doesn't matter for the web as you can set resolution at the last minute.

I know, that was maybe stupid of me. I think I read somewhere that this bogs the files down if you set it too high. But – if the drop shadow is live I suppose it's not rendered as a bitmap until rip time or PDF-export?

Yani:

It does sound like the shadow and bitmap got combined into a single object and that object would likely be rendered at the resolution of the item with the lowest ppi.

Yes, it looks like that. When you apply a drop shadow to a bitmap, they create a group together.  However in this case there was another object involved as well and that might be the culprit because I had other images with drop shadows in this issue, and they did not get downsampled.

I will do a test, but I have been bogged down with work today regarding several issues. Amongst them another PDF issue with invisible bitmaps from the opposing page being stored even if you extract only one page.

Lars Forslin:

Amongst them another PDF issue with invisible bitmaps from the opposing page being stored even if you extract only one page.

Does it hit the page as it or hit the page if you remove a crop?

I'll be on the look out for that issue (shadow ppi) now thanks Lars. If nothing else it should be a warning to look out.

Yani:

Does it hit the page as it or hit the page if you remove a crop?

Err... I'm not sure what you mean here. I'll explain (and I'll do some screen shots later).

Suppose you make a publication with facing pages. You make a web PDF version out of it from which you want to extract say one page for publishing on the web. On the page i question you have no images, but on the opposing page you have. Now when you save that single page you find that it is 600 kB - just plain text! Then you run a Preflight test in Acrobat and find that there are images listed that are invisible. then you zoom out in Acrobat and drag-select with the TouchUp Object Tool in the area where the opposing page was to be, and you'll find that all of the objects will show up as wireframes. You can select all that and then press Delete and resave the page and you'll find that it's suddenly only 200kB!

Another way of proving this: select the invisible image by using the common Select tool and then Ctrl+C. Now open Photo-Paint and paste as new from clipboard. Voila! The image that was not on your page is there!

I don't know what this is all about, but I have a suspicion that this comes from the pretty bad facing page implementation in Draw. You can also see strange things in the PDF thumbnails when using facing pages etc. etc. Something that indicates that things are not quite alright with facing pages in PDF files.

Lars Forslin:

But – if the drop shadow is live I suppose it's not rendered as a bitmap until rip time or PDF-export?

Anyone would suppose that CorelDRAW will also re-render shadows when the Rendering Resolution is changed, so they are rendered at the new resolution. Actually CorelDRAW will not; you have to push CorelDRAW to re-render them by editing their parameters or control objects.

If you change the Rendering Resolution at the last minute without pushing CorelDRAW to re-render them, they will be published into the PDF in their old resolution (i.e. Publish To PDF bitmap downsampling settings will be applied to their old rendering resolution).

I "feel" this might apply to CorelDRAW X4.

Lars Forslin:

I think I read somewhere that this bogs the files down if you set it too high.

1. Reconstruct, rebuild, or redesign the work so CorelDRAW and my machine will be able to handle it.
2. Reduce the Rendering Resolution to gain performance at the expense of output quality.

I always choose the first (if I happen to face this situation).

You may also set a low Rendering Resolution as a preview, and change it (and push CorelDRAW to re-render the shadows) before outputting, which doesn't feel right for me. Maybe this is a feature request, Preview Rendering Resolution set separately from the Output Rendering Resolution.

I suppose you can also break the drop shadows apart from the group and then downsample it if you want a less heavy bitmap. Then it wouldn't affect the object it was grouped with.

If I want a "less heavy" shadow, I decrease the Rendering Resolution, and keep the shadow as Drop Shadow (live or interactive).

If I want to have a separate bitmap, I break the shadow apart.

I'm checking the PowerClipped bitmap problem; it happens with PDF/X-3 and PDF 4, where the PowerClipped bitmap is converted to a bitmap at same resolution of the shadow of its container; at the Rendering Resolution.

In the attached image, a 200 dpi bitmap was placed inside a circle which has a Drop Shadow in CorelDRAW X3 SP2, then published to PDF.

• In all the experimentations,
  1. CorelDRAW Rendering Resolution was 300 dpi
  2. CorelDRAW Page Resolution was 96 dpi (no effect on the results).
  3. No bitmap downsampling in the Publish To PDF Settings.

• Even if the shadow was broken apart, converted to bitmap and published to PDF/X-3, I got same results under PDF/X-3.