Exporting Transparency Properly

[myuserid7]

When I have an image with transparency, when I export to EPS it always converts the image to bitmap format. Is there any way of getting CorelDRAW to render the transparency as scalable objects before exporting?

Thanks

 

[Brushman]

When you say image do you mean as in already a bitmap format or as in a vector drawing. A transparency/lens on a drawing which is in front of a vector ie lettering will convert to bitmap. If you describe the job with a little more detail may be able to help further.
Alan D

 

[myuserid7]

I'll provide more detail:

I have a vector drawing made up of several simple transparent vector polygons, and no bitmaps. When I use the "Export" command to export to an EPS vector format, then anything with a transparency is rendered as a bitmap. Is there any way to get CorelDRAW to break down the transparency into vector objects (e.g. two overlapping rectangles would become three different coloured polygons), or any way at all that I can have the output image as a vector EPS, and not a huge low quality bitmap? I hope that that is clearer.

 

[Brushman]

How are you checking the integrety of the eps. If you are importing back into Draw using the eps filter you will see a low resolution header used by Quark and similar for position and size onlt, outputing to Postscript device only will print the ostscript file as expected, a non postscript device will print the header. To import the eps as vectors use the Postscript interpreted filter, you may get a colour shift though.
Alan D

 

[myuserid7]

I'm checking the integrity using GSView, and by the sheer size of the files. If I remove all transparency then the file is about 20k; with transparency 1.5Mb, and this is just for a test file involving nothing other than a red square and a transparent green circle.

I've been experimenting and it seems that if I use the interactive transparency tool it renders it as a bitmap, but if I use the Lens transparency then it seems to be rendered as the constituant vectors. I'm going to have to do some more experimenting to see if this really is the case. Thank you for your help Alan.

 

[javabearSTL]

also, what do you mean by "transparency?" EPS does not support transparency, per se. What are you trying to achieve with this so-called "transparency?" What is the end purpose for the file? Yes, if you use the "interactive transparency" tool, drop shadows, etc., those items would have to be merged together into a bitmap for the effect to display/print properly when exported to EPS, that's just the nature of postscript. Illustrator and Freehand files would do the same thing. So that's why you need to give more info, i.e. what are you trying to do/what's the final outcome for, etc.

 

[myuserid7]

The EPS is actually for a diagram in LaTeX, so it is to be imported with dvips. My diagram is a picture of a green cuboid partially inside a transparent red cube. The transparency is just so that the green cuboid can be seen inside the red cube. All my transparencies are simple uniform ones.

I'm aware that EPS doesn't support transparency, but surely there is some way of breaking down the curves and rendering them as non-transparent objects (I don't need the output file to be editable).

For example, if I have a red square transparent green square overlapping, then it could be converted into three vector shapes with no transparency: a red L-shape, a reddish-green intersection of the two (square) and a green L-shape:


[tt]
+------+
|GGGGGG| +---+ +------+
+---+--+GGG| |RRR| |GGGGGG|
|RRR|RG|GGG| ==> |RRR+--+ +--+ +--+GGG|
|RRR+--+---+ |RRRRRR| |RG| |GGG|
|RRRRRR| +------+ +--+ +---+
+------+
[/tt]

(Output shapes have been separated for clarity).

I hope that this is clearer. Am I barking up the wrong tree? I really don't want to have to resort to using low-quality bitmaps.

Thanks,

Jonathan

 

[Brushman]

Put your 2 squares on screen do an 'intersect' colour the 3rd bit any colour you choose - or 2 squares on screen - put transparent lense on one to show overlap bit - export as eps - import eps using postcript interpreted filter.
Alan D

 

[javabearSTL]

if you were importing with the EPS filter, well, that is just a "placeable" filter and will only show the low-res bitmap header of the file. It will also only print that header unless you print to a postscript device.

Another way to do this would be to have your two squares overlap, then on the property bar select Intersect (instead of Trim, etc) and then just color the new square something else. - that would keep all items as vectors and not resort to any "transparency.

 

[myuserid7]

For the simple example, intersection is fine, but my diagram is a bit complex to have to do that for each component:

It could be done for my image, but why it can't be automated I don't know - I'm sure that it wouldn't be difficult to code. I also have a few more diagrams that are much more complex than this, and it would take me hours to intersect and colour them all.

 

[javabearSTL]

At no point did you say you were trying to do technical drawings. You might look over at

http://www.isocalc.com

- Nick Wilkinson has some tools there along with his IsoCalc app for Draw the might be able to help you.

 

[myuserid7]

I didn't supply the image to begin with because I couldn't see any way of attaching an image; the site only says how to do this when you click "Preview Post", which I hadn't done before. As for just providing a link to an image, my genuine mistake I should have thought about it before. It is easy to think about in retrospect.

I hope that this clarifies things. Once again, thank you for your time.

 

[myuserid7]

IsoCalc looks interesting, I'll check it out. I think perhaps maybe a little bit too over the top for my drawings though - it's not really technical drawings that I am doing, more just a few diagrams for a technical paper. Thanks.