Patch Code - Dynamsoft Barcode Reader SDK

What is a Patch Code?

Originally created by Kodak to help processing applications separate large documents, the patch code appears at page/section breaks to give instructions such as when to change from single-sided to duplex scanning.

Patch Code

A patch code is a type of barcode that consists of alternating black parallel bars and spaces. Once scanned, typically with a TWAIN driver, it can carry out a predefined action.

However, unlike most barcodes, Patch Codes do not contain any encoded data. While they are printed on all four edges of a document, only one is ever read. This allows the code to be read even if the page is upside down or rotated.

Additional barcodes, such as Code 39, can also be added to the page to convey encoded information.

There are six distinct barcode patterns, each consisting of varying arrangements of wide and narrow bars:

  • Patch 1 (wide, wide, narrow, narrow) used for post-scan image control
  • Patch 2 (wide, narrow, narrow, wide) assigns image level 2 to the current document
  • Patch 3 (wide, narrow, wide, narrow) assigns image level 3 to the current document
  • Patch 4 (narrow, wide, wide, narrow) used for post-scan image control (toggle patch)
  • Patch 6 (narrow, narrow, wide, wide) used for post-scan image control
  • Patch T (narrow, wide, narrow, wide) assigns predefined image level to the next document (transfer patch)

Where is a Patch Code used?

Where they really shine is in batch scanning documents. This is common across many industries where a large number of documents need to be processed using a document scanner and then organized in a digital format.

Instead of running multiple scans, which would require scanning each document separately, the documents are loaded into the scanner with a Patch 2 separating the different areas of the document.

If you’re scanning hundreds of documents such as loan applications, or tax information, you can incorporate a Patch 2 codes on the first page to indicate the start of a new form. Or, if you need to separate different sections of the document, you can prepare the document by inserting these barcodes into the different sections, which instruct the capture software to organize documents into separate files.

Another application is to use Patch 4 (color toggle) to separate black and white pages from colored pages. It works by placing Patch 4 codes before and after the color sections.

Patch Code Patch Code

The following process is carried out by the document capture software:

  1. 1. The scanner begins scanning in black and white
  2. 2. When it reaches the first Patch 4 code, it toggles the scanner to scan the next section in color
  3. 3. When it encounters the second toggle patch, the scanner reverts to scanning the pages in black and white

The action taken by the document capture software upon recognizing a Patch Code is configurable to a given application. For instance, the toggle patch may be used to toggle between high and low resolutions, as well as single- or multi-sided scanning.

  • Patch Codes 1, 4, and 6 are used for color or multi-feed detection
  • Patch Code 2 is used for document separation
  • Patch Code 3 is used for batch separation
  • Patch Code T can be used for either document or batch separation

How could Dynamsoft help you with Patch Code?

Dynamsoft barcode reader enables you to efficiently embed high-speed and reliable barcode reading functionality in your web, desktop or mobile application using just a few lines of code.

Download the free trial SDK, explore our helpful resource center including sample codes, tutorials, guides and more to get started.