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Importing & exporting BMP files (very simple stuff)

Last post 06-09-2008 6:21 by TOBY MARTHEWS. 0 replies.
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  • 06-09-2008 6:21

    Importing & exporting BMP files (very simple stuff)

    Dear Corel Draw,

     

    I have found a problem with Corel Draw’s importing and exporting of BMP files. I’ve made an example here using a very small bitmap (can't post BMP files to this forum, so have attached the PNG equivalent, which you could convert back to BMP to follow these steps, or alternatively take any BMP file in 16 color format because I think the oddities will happen very similarly).

     

    1. Start with ExampleMap.bmp, created in MS Paint, a 96 dpi image with 176x206 pixels, 16 colors. File size is 17.8 KB according to Right-click-> Properties.

                All I’m going to try to do is import this into Corel Draw X4 and immediately export it to recover the original bitmap.

     

    2. So: I opened ExampleMap.bmp in Corel Draw X4 and exported immediately as a BMP Graphic1.bmp (without anti-aliasing).

                ** FIRST ODD THING: while exporting, Corel Draw said the original file size (size of ExampleMap.bmp) was 106 KB, which was wrong **

                ** SECOND ODD THING: Corel automatically changed the 16 color BMP into a 24-bit BMP, hence Graphic1.bmp is 6x the size of ExampleMap.bmp (106 KB) **

     

    3. So, I re-exported the image as a 16 color BMP Graphic2.bmp

                ** THIRD ODD THING: while exporting, Corel Draw says the original file size was 17.7 KB (correct now, but why was it different before? the original file is the same!) and that Graphic2.bmp will be the same size (but what it actually saves is a file 36.2 KB??) **

                ** FOURTH ODD THING: If you load Graphic2.bmp into Paint, you find that all the red has changed to grey - the file is not a copy of the original at all! **

     

    4. So, I loaded Graphic1.bmp into Paint and saved it as a 16 color BMP Graphic3.bmp. This worked fine and the final file Graphic3.bmp is the right size (17.7 KB) and has the same colours as the original.

     

    In conclusion, the only way to import and re-export a simple 16 color BMP file is to import it, save as a 24 bit BMP and then load that into Paint and change back to 16 colors.

     

    My question is: is this really the only way to do this? Dealing with a temporary file of 6x the size is a problem for me with my very large maps. Also, why can Paint do something that Corel can't?  Am I missing something basic?

     

    Toby Marthews


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