Image size limits

Version 12

Version 12 imposed both global and module-specific limits. The global limits for loading images were 8400 pixels and 22 inches for both width and height. Some of the OCR modules had lower hard-coded limits:

  • MOR: 5440 pixels

  • MTX: 6688 pixels, image area limti: 20 megapixels - practically around 4000x5000 pixels.

Version 15

With version 15, fundamental changes were introduced in the image handling algorithms in all modules to allow to them to deal with practically unlimited image sizes: 32000 pixels in both dimensions. This limit was set because image coordinates must fit into a signed short integer. There was a code that checked the size of images being loaded, and returned an error if the images exceeded certain limits

  • In pixel dimensions

  • In actual length

  • In height (pixel dimensions divided by DPI)

These limits were determined by settings that could be changed by the user. See the following sections under RecAPI help Related pages > List of all the RecAPI settings:

  • Kernel.Img.Max.Pix.X 8400

  • Kernel.Img.Max.Pix.Y 8400

  • Kernel.Img.Max.Inch.X 28

  • Kernel.Img.Max.Inch.Y 28

The goal of these default values for the image size limit was to prevent the time consuming processing of huge images, for example when the kit was used in an unattended, background process recognizing all the files on a machine. If an application was required to process images bigger than these limits, they could be set to any value (up to 32000 for the pixel count). See section Settings Manager Module in the RecAPI help.

The following table summarizes testing done with version 15, when recognizing pages , using the PLUS3W module in Accurate mode and exporting to XML formatted output.

Similar tests are currently being performed on version 16. European page sizes were used - for each move from A4 to A3 to A2 and so on the page area doubles. The results for A4 practically apply for the US page size 'Letter' (8.5 x 11 inches).

Page Size Image Type Resolutions

A4

8.3 x 11.7 inches

Black-and White (BW) Up to 2400 dpi
4- or 8-bit grayscale, 8-bit color Up to 1600 dpi
24-bit True Color Up to 1200 dpi

A3

16.5 x 11.7 inches

BW, 4- or 8-bit grayscale, 8-bit color Up to 1600 dpi
24-bit True Color Up to 1200 dpi

A2

16.5 x 23.4 inches

BW, 4- or 8-bit grayscale, 8-bit color Up to 600 dpi
24-bit True Color Up to 600 dpi

A1

33.1 x 23.4 inches

BW, 4- or 8-bit grayscale, 8-bit color Up to 600 dpi
24-bit True Color Up to 400 dpi

A0

33.1 x 46.8 inches

BW, 4- or 8-bit grayscale, 8-bit color Up to 400 dpi
24-bit True Color Up to 300 dpi

These values are indicative only, since performance is strongly influenced by characteristics of individual image files, the processor used and the computing environment. These tests were done on a hyper-threaded machine with 2 x 2.4 GHz and 1GB of RAM.

Version 16

Version 16 retains the limit of 32000 pixels and the default of 8400 pixels, however the limitation in inches is removed, to avoid the rejection of large but low resolution images, whose pixel count is still acceptable. In exporting large pages, be aware that Microsoft Word will not accept RTF files with either lateral larger than 22 inches.

It is important to understand that memory limitations on a given system may limit the size of the images that can be successfully processed and that this may restrict image size to below the 32000 pixel width and height limits.