A while ago a V11 user brought to our attention a problem using images in CAD4U. The Insert Bitmap functionality has been available in CAD4U since version 6 and although we have added support for JPEG there has been little change since then. The user reported that they were having problems with using the transparency setting to hide the ‘white space’ around the images in question, and they were coming out as black rather than ‘transparent’. The problem caused some soul searching here and at C-Technik. It would appear that when printing to Postscript devices (which includes PDF output) there are some weaknesses in the way in which this works.
C-Technik reported the following:
“… We have spent some hours by testing different versions of CAD4U re. ‘the transparency problem’, here is our resulting information.
Transparency works just fine in all the CAD4U versions, tested from V.6 until V.11 and there is NO problem, which can be fixed by us.
The PDF/postscript format doesn’t support this kind of transparency. We have tested it with Adobe PDF and with PDF Machine. It’s always the same result.
If you PRINT a CAD4U drawing with transparency to a real (non-postscript) printer, this works fine. Even with overlapping bitmap transparencies!
The result of this test is, that PDF format is not usable to transfer CAD4U drawings including TRANSPARENT bitmaps. It’s very good for vector drawing data, but especially transparency is NOT SUPPORTED in this way!”
Interestingly, if the print option ‘Grayscale bitmaps (no transparency)’ is used with Postscript output then everything works OK which is our advised workaround. Fixing the problem is not so easy, as it is dependent upon the Postcript printer language. We now believe that it is possible to get it right by first creating the print image on the host before sending to the printer … watch this space.
The application of CAD4U above was to create sales type documents which included a drawn site layout and product images of items which were placed within the layout. Our advice in these circumstances would be to use a product such as Word to create the document and use the Clipboard>Drawing Data functionality in CAD4U to insert the drawing into the Word document. It’s a question of ‘horses for courses’ in that CAD4U is great at producing drawings and products such as Word are good at ‘laying out’ artwork for this type of document.
One last point … I understand from the user that this problem manifested itself in V6 but this is the first time they have reported the problem. If the problems go unreported in this way then they certainly won’t be fixed!