How to Read PDF417 bar-codes from the image?

I am working on bar-code (PDF417) detection and recognition from a stack of boxes. The size of the bar-codes are relatively very small as compared to the Boxes. If I place the camera very near to the stack of boxes I can cover only one box and read only one bar-code. If I place the camera a little far such that the image frame contains five boxes, I couldn't able to detect any boxes.

How can I address this problem, and what are the possible ways to solve it.

Conditions:

The barcode size can not be changed

We have the freedom to select the camera

[Walter Roberson]

Can you take multiple frames? If so then does the camera move or the boxes move?

[Shaik Ahmad]

Hi Walter Roberson sorry for the delay. I have tried that option. If the frame contains one or two boxes then I am able to read it, but if there are more than two, I coudn't able to read it.

[Walter Roberson]

Choose a distance at which only one barcode is visible at a time, then move the camera or move the boxes so that other barcodes come into view one at a time.

[Shaik Ahmad]

In the preesnt scenario the boxes are placed in a pile (5 boxes one on top of other). I can't move the boxes vertially. And camera should be fixed to a specific position.

[Walter Roberson]

Well, you appear to have a few choices:

• change the scenario so that the boxes can move vertically; or
• change the scenario so that the camera can move; or
• add more cameras; or
• use a higher resolution camera; or
• give up

There is a range of distance / sizes for which it could potentially also be effective to use image enhancement techniques: although you might currently be recording a blur, in small regions the pattern of the blur might be distinctive under the assumption that the original is two specific colors. This only gets you so far, though: at some distance / resolution combination the information is simply no longer there in the image.