The first step in obtaining better quality conversions is to check the original images or documents in the application where they originated such as Adobe Acrobat or Microsoft Word. If the original application is not available, try another viewer. If the quality is bad for the original image, then you may not be able to obtain any better quality in the conversion.

If this is a simple bitmap format such as TIFF, you can try adjusting the sharpening, contrast and brightness. To improve the quality of a 1-bit file format document, first convert it to gray scale using IMG_promote_8().

If the source image or document is vector or it is composed of text and drawing commands such as PDF, Word, or AFP, you can set the conversion to be 1-bit or increase the dots per inch using IMGLOW_set_document_input(Dpi, bits_pix, format). Please see IMGLOW_set_document_input(int, int, int) in the RasterMaster Java API for more information.

Please note that a higher resolution will almost always yield a better quality conversion but will probably result in a larger output file size.

Also it is common to convert to TIFF_G4. This is a 1-bit per pixel format. Make sure that if you are converting from a color image, that it is mostly text. There will be a noticeable loss in quality for pictures or color graphics such as logos when converting a color image to a 1-bit per pixel format. Text will usually work well.

If your document requires color, then try saving to a color output format such as TIFF_Packbits, TIFF_ JPEG or TIFF_LZW.

The output quality of your output document may be much lower than the original document if you convert a high quality image to a low quality output such as TIFF_G4_FAX. Please see the following suggestions to improve the quality of the output document:

Choose a different output format such as TIFF_LZW to produce an output document with sufficient pixel depth.Supported File Formats shows a list of file formats and their supported bit depths.

Use one of the following methods prior to decompression to increase the output dots per inch (DPI) or bit depth. Please see Image Quality Manipulation for more detailed information.

  • IMGLOW_set_document_input(int dpi, int bits_pix, int format) converts PDF, Word, Excel, PCL and AFP formats. Please see IMGLOW_set_document_input(int, int, int) for more information.
  • IMGLOW_set_pcl_input(int dpi, int bits_pix) converts PCL formats only. Please see IMGLOW_set_pcl_input(int, int) for more information.
  • IMGLOW_set_pdf_input(int dpi, int bits_pix) converts PDF formats only. Please see IMGLOW_set_pdf_input(int, int) for more information.

Use the color promotion method, IMG_promote_24(void), to promote 1-bit, 4-bit and 8-bit images to 24-bit images. Please see Color Manipulation Methods for more detailed information.