Sometimes you scan a document and it prints back out at a fraction of the size. It looks crazy. It used to frustrate me and, in my day job, I was using other people’s expensive scanning software and having these problems. I could certainly understand a user’s frustration with CmdTwain getting this wrong.<\/p>\n
The fix to CmdTwain is incidental to this article. It was the catalyst but this article is broader than CmdTwain. (If you are only using CmdTwain 1.02 or later, you don’t need to read this article.)<\/p>\n
Solution<\/h2>\n
If the DPI resolution of a bmp file from another program is wrong and you want to fix it, you can use get_dpi<\/a> to check the file and set_dpi<\/a> to change it.<\/p>\n Both of these links are to ZIP files containing a program and a Borland C runtime DLL. Their use is straight forward:<\/p>\n “get_dpi” will tell you the current DPI resolution. When run, they look like this:<\/p>\n When you run get_dpi on a bitmap file which doesn’t have DPI set at all, you’ll see 0 for the values. Shockingly, the fastest way to get an incorrect bitmap like this – is to use MS Paint.<\/p>\n The result looks like:<\/p>\n\n
\n“set_dpi” will change it.<\/p>\nWhat it Looks Like<\/h2>\n
\r\nC:\\Test2>get_dpi\r\nGet_dpi Ver 1.00\r\nCopyright (c) 2013 GssEzisoft\r\n\r\nUsage: get_dpi filename.{jpg|jpeg|bmp}\r\n\r\nC:\\Test2>get_dpi 67.bmp\r\nx= 400 DPI, y= 400 DPI\r\n\r\nC:\\Test2>set_dpi\r\nSet_dpi Ver 1.00\r\nCopyright (c) 2013 GssEzisoft\r\n\r\nUsage: set_dpi filename.{jpg|jpeg|bmp} xDPI [yDPI]\r\neg1 : set_dpi fred.jpg 300\r\neg2 : set_dpi demo.bmp 300 400\r\n\r\nC:\\Test2>set_dpi 67.bmp 300\r\n\r\nC:\\Test2>get_dpi 67.bmp\r\nx= 300 DPI, y= 300 DPI\r\n\r\nC:\\Test2>\r\n<\/pre>\nUnspecified DPI<\/h2>\n
\r\nC:\\Test2>get_dpi 20x20-red.bmp\r\nx= 0 DPI, y= 0 DPI\r\n\r\nC:\\Test2>\r\n<\/pre>\n
![\"bitmap-file-properties-with-zero-dpi\"](\"http:\/\/www.gssezisoft.com\/main\/wp-content\/uploads\/2013\/06\/bitmap-file-properties-with-zero-dpi.png\")
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