MRC image compression level comparison

The following samples demonstrate image quality with different MRC compression levels. Zoom in the samples to inspect the following details:

• Foreground image quality

• Background image quality (behind the text)

• Text contour

Source image without lossy compression

OmniPage CSDK 22.0 PDF MRC Level 5 Benefit: Provides good image quality, text contours are smooth even at high zoom levels. Disadvantage: Reduces background detail, results in larger file size.

OmniPage CSDK 22.0 PDF MRC Level 1 Benefit: Results in small file size. Disadvantage: Reduces the background detail to the minimum, provides low image quality, artifacts strongly appear.

OmniPage CSDK 22.0 PDF MRC Level 2 Benefit: Results in small file size. Disadvantage: Strongly reduces background detail, provides low image quality, artifacts appear.

OmniPage CSDK 22.0 PDF MRC Level 3 Benefit: Results in small file size, but slightly larger than Layer 2. Disadvantage: Reduces background detail, provides low image quality, artifacts may appear.

OmniPage CSDK 22.0 PDF MRC Level 4 Benefit: Keeps most of the background detail, provides fair image quality. Disadvantage: Results in double file size compared to Layer 2.

Level 5 compression provides the best graphics and characters. To improve the look of MRC compressed PDFs, Level 5 converts the 300 dpi gray image to 900 dpi black and white on textual areas, thus creating a 900 dpi selector layer. The high-resolution selector layer results in much smoother character boundaries, even when the user zooms the image.

OmniPage CSDK 22.0 PDF MRC Level 5 - text zoomed in

OmniPage CSDK 22.0 PDF MRC Level 3 - text zoomed in

The following table compares the uncompressed file size with the file sizes achieved by different MRC Levels. These figures show that Level 5 compression provides a PDF file more than a hundred times smaller than the uncompressed source TIFF. Level 3 compression results in a file 455 times smaller than the original.

File size in KB by compression level