I am trying to learn how to make tiled backgrounds by cutting a picture into four quadrants and swapping the lower left to upper right and lower right to upper left. That process is fine and I am doing well with it. However, when I export the file as a .jpg or .gif and then try to display it as tiled, a white line appears between each of the tiles. I've double checked the Corel file to make sure that each quadrant is exactly on the border of the "page" but can't get that white line to disappear on my desktop. Any suggestions?

Hmmm, first thing that comes to mind is that there are small spaces between the tiles. My suggestion is to zoom in VERY close and have a look. You cannot always rely on object snapping to close gaps. Zoom in and have a look. Let me know how you make out. Try that first and if it doesn't help we'll take it from there. Hope that helps! 

I think this white line comes from 'Anti-aliasing'.

 

I usually draw a rectangle behind my objects, bigger than the objects. Then export as bitmap (any proper format). In Corel PHOTO-PAINT, I crop it to get rid of the extra space.

 

For me, it is a big and irritating problem.

In version 11, it was 4 "white lines" (one per each side). In X3, it's just two lines on the left and the bottom.

 

I recorded a script, in Corel PHOTO-PAINT, to get rid of one-pixel-thick frame for bitmaps exported from CorelDRAW.

Yes, I looked at this.  I had some trouble at first because I had extra nodes on a few of my quadrant bitmaps that were extended beyond the page itself.  I fixed all of those and still had the issue.  Thanks for your help.

Ha!  Now you're over my head!  But you're absolutely right, it IS the anti-aliasing.  I did some further experimenting.....

I have the same version of CorelDraw at work as I do at home.  However, when I "fill" a page with a bitmap at work, the picture covers the page outline and does not cause the white lines upon exporting, as long as I uncheck the anti-aliasing box on the .jpg exporting page.

At home, the bitmaps fall just inside the outline of the page and the lines show up even if I uncheck the anti-aliasing box.  I'm running Windows XP Professional at work and Windows XP Home edition on my laptop but I don't know if this would have any effect on that.

I'm going to experiment to see if there are settings that address this issue but I'm not very experienced in this aspect.  Any suggestions?

 

I think I figured it out.  I played with the anti-aliasing a little bit and could only reproduce the problem about half the time.  When I did get it to work, the lines were gone but there were some subtle but noticeable problems right in the middle of the tiled image where it looked like rows of pixels were missing.

And then I decided to really zoom in on the pixels.....

When you crop a pixelated picture in Corel, sometimes the pixels that run along the edge of a page are incomplete.  I think that CorelDraw is filling in these incomplete pixels with the background color when you export to a .jpg with the anti-aliasing checked.  When you uncheck the anti-aliasing, it simply doesn't fill in those pixels but the cropped edges still have only partial pixels.

I started over with Corel Draw and changed all of my grid settings and page dimensions to pixels.  It immediately fixed the problem!  Now I'm cropping to only full pixels and the anti-aliasing checked or unchecked doesn't effect the finished .jpg.  Yeah!

 

In CorelDRAW 11

 

Lines appear depending on whether you are exporting vectors or pixels from CorelDRAW to a bitmap format.

 

When exporting vectors, lines will appear if anti-aliasing is checked. When exporting rectangular bitmap, no lines will appear whether anti-aliasing is checked or not.

 

1. Anti-aliasing: checked
2. Type of image in CorelDRAW: vectors
3. Lines: appear tinted with background color

 

 

In CorelDRAW X3

 

Lines appear if anti-aliasing is checked even if you change the page size and units to pixels. No deference between exporting vectors or bitmap; anti-aliasing will create those lines.

 

 

What I noticed

 

Anti-aliasing lines appear depending on

 

1. CorelDRAW version
2. Type of image in CorelDRAW 11 (vectors or bitmap)
3. Anti-aliasing
4. Document background color

 

And are independent from

 

1. Operating system: Windows XP or Home
2. Document and Grid units
3. "page outline" coverage: whether the image extends beyond page borders or not.
4. Type of output bitmap (.JPG or .TIFF…)

 

Not sure…

5. "incomplete pixels"

 

 

NOTES

 

1. Remember, if you are exporting a bitmap object, it is (mostly) already anti-aliased. You can export with anti-aliasing unchecked.
2. If you are exporting bitmaps, but they were inside PowerClips, lines will appear even in CorelDRAW 11 (you are exporting vectors).
3. Changing the document background color helps efficiently if your image has same and one color along all its edges.

Background color should interfere in anti-aliasing algorithms only if it is visible within the boundaries of the objects being exported or converted to bitmap; not along all edges.

 

In CorelDRAW, you can't get anti-aliased bitmap exported from vector objects without annoying and artificial one-pixel-width frame.

 

Do I have to "work around" to get a colored rectangle?