Get the resolution (in DPI) of a *.jpg image (Views: 30)
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Problem/Question/Abstract: How to get the resolution (in DPI) of a *.jpg image Answer: procedure GetResJpg(JPGFile: string); const BufferSize = 50; var Buffer: string; Index: integer; FileStream: TFileStream; HorzRes, VertRes: Word; DP: Byte; Measure: string; begin FileStream := TFileStream.Create(JPGFile, fmOpenReadWrite); try SetLength(Buffer, BufferSize); FileStream.Read(buffer[1], BufferSize); Index := Pos('JFIF' + #$00, buffer); if Index > 0 then begin FileStream.Seek(Index + 6, soFromBeginning); FileStream.Read(DP, 1); case DP of 1: Measure := 'DPI'; 2: Measure := 'DPC'; end; FileStream.Read(HorzRes, 2); HorzRes := Swap(HorzRes); FileStream.Read(VertRes, 2); VertRes := Swap(VertRes); end; finally FileStream.Free; end; end; |