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August 2006
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2006.08.25 05:56 "Re: How to find/read resolution values of TIFF image file", by Toby Thain
On 25-Aug-06, at 1:40 AM, muthu kumar wrote: > Dear Friends, > > I am new to Tiff file processing. > I can read the tiff file and i used the functions to > assign the resolution of the image as follows, > > uint32 w,h,bpp, xres=0, yres=0, resunit=2; > > TIFFSetField(tiff,TIFFTAG_RESOLUTIONUNIT,(uint16)resunit); > TIFFSetField(tiff,TIFFTAG_XRESOLUTION,(float)xres); > TIFFSetField(tiff,TIFFTAG_YRESOLUTION,(float)yres); > > and it works well. But when i tried to read the > resolution using the functions > > uint32 w,h,bpp,xres=0, yres=0, resunit=0; > > TIFFGetField(tiff, TIFFTAG_XRESOLUTION, &xres); > TIFFGetField(tiff, TIFFTAG_YRESOLUTION, &yres); > TIFFGetField(tiff, TIFFTAG_RESOLUTIONUNIT, &resunit); > > I got the results like > xres = 0x42900000 or xres = 0x43960000 > > I know that the > xres = 0x42900000 for dpi = 72 > and xres = 0x43960000 for dpi = 300 > > But I want to know how to calculate the dpi values > from this hex values. Is there any fomula for this. > Or the function i am using is wrong. If xres and yres are defined as 'float' type, you should see what you expect. --Toby > > Please help. > > Thankyou. > > Muthu.J > muthupyr@yahoo.com > > __________________________________________________ > Do You Yahoo!? > Tired of spam? Yahoo! Mail has the best spam protection around > http://mail.yahoo.com > _______________________________________________ > Tiff mailing list: Tiff@lists.maptools.org > http://lists.maptools.org/mailman/listinfo/tiff > http://www.remotesensing.org/libtiff/