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#1 Posted : Wednesday, March 26, 2008 1:38:04 AM(UTC)

Mahesh  
Mahesh

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Posts: 4


Hi
Is LT 15 supports the DPI feature? if yes then upto how much value i can set and with which API i can do that?
Thanks in advance,
Mahesh

 

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#2 Posted : Wednesday, March 26, 2008 6:48:20 AM(UTC)

Adam Boulad  
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Mahesh,




If
an image is loaded in memory by LEADTOOLS, the X and Y DPI are just a pair
numbers. You can set them to almost any value between 1 and infinity. It does not affect the pixel image size.




However,
if you are asking about loading some types of images at a certain DPI value,
such as PDF, in this case, the loading DPI affects the image size. In this
case, LEADTOOLS does not have restrictions on the DPI you set, but the higher
it is, the larger the resulting image will be, and it will require more memory.
This means the final limitation will depend on Windows and your machine resources, such as free memory.






Additional information:
When
loading an image into the LEADTOOLS Raster toolkits, it is always loaded as pixels (raster) bitmap image.


For
some types of images, such as BMP, GIF, TIFF and JPEG, the data stored in the
image is originally in pixels, and the DPI is just a number that does not
affect the width and height in LEADTOOLS. This means an image that's 800 pixels
wide and 600 pixels high will always load as 800x600 pixels in LEADTOOLS, regardless of what the DPI resolution values are.


When
loaded, if the image has DPI values stored in the file, LEADTOOLS will load
these 2 numbers as the XResolution and YResolution members of the BITMAPHANDLE structure.


If
no values are stored in the file, LEADTOOLS will simply put the value 150 into these 2 members.


If
you change the values yourself to any number, the actual pixel width and height
are NOT affected automatically. If you want to change them, you must also call the L_SizeBitmap() function.


 


For
some other formats, such as PDF (if you own the PDF plug-in) and also for
vector formats (if you own the vector toolkit and load the images as Raster)
the actual Width/Height will depend on the loading DPI, or the rasterization
window size. The image is converted to raster during loading. In the case of
PDF and PostScript the resolution of the loaded files will be 72 by default.
The loading resolution can be changed by using the L_SetPDFOptions, and set the nXResolution and the nYResolution parameters.



Again,
after loading, even with PDF and PostScript, the image becomes a raster (pixel)
bitmap, and changing the DPI after that will NOT have any effect on the pixel dimensions.

 
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