Declaration
TIOPDFCompression = (ioPDF_UNCOMPRESSED,
ioPDF_RLE,
ioPDF_G4FAX,
ioPDF_G3FAX2D,
ioPDF_JPEG,
ioPDF_LZW
);
Description
| Value | Description | Support Color? | Support Monochrome? |
|---|---|---|---|
| ioPDF_UNCOMPRESSED | No compression |  | |
| ioPDF_RLE | Run length compression |  | |
| ioPDF_G4FAX | G4Fax (black & white images only) | | |
| ioPDF_G3FAX2D | G3Fax (black & white images only) | | |
| ioPDF_JPEG | DCT-JPEG (color images only) | | |
| ioPDF_LZW | LZW compression | | |
Note:
◼ Monochrome images (BitsPerSample and SamplesPerPixel = 1) do not support ioPDF_JPEG. If specified, ioPDF_G4FAX will be used instead
◼ Color images do not support ioPDF_RLE, ioPDF_G4FAX or ioPDF_G3FAX2D. If specified, ioPDF_UNCOMPRESSED will be used instead
◼ If your image contains transparency (HasAlphaChannel = True) and is not monochrome, use ioPDF_LZW or ioPDF_UNCOMPRESSED to include it in the PDF. ioPDF_JPEG can also be used but artifacts may be visible. The Alpha channel makes the file size much larger, so you may want to remove it
◼ For ioPDF_JPEG, you can specify the JPEG quality and other properties using: JPEG_Quality, JPEG_Smooth, JPEG_ColorSpace, JPEG_DCTMethod, JPEG_OptimalHuffman
Examples
// Convert monochrome TIFF to PDFImageEnView1.IO.LoadFromFile('D:\input.tif');
ImageEnView1.IO.Params.PDF_Compression := ioPDF_G4FAX;
ImageEnView1.IO.SaveToFile('D:\output.pdf');
// Convert full color PNG to PDF
ImageEnView1.IO.LoadFromFile('D:\input.png');
ImageEnView1.IEBitmap.RemoveAlphaChannel( True ); // Discard any alpha channel if not needed to reduce file size
ImageEnView1.IO.Params.PDF_PaperSize := iepA4;
ImageEnView1.IO.Params.PDF_Compression := ioPDF_JPEG;
ImageEnView1.IO.Params.JPEG_Quality := 90;
ImageEnView1.IO.Write('D:\out.pdf');