Megapixels and Resolution (not related to printing photos)

[kenh000]

Hi all,

I've been searching the internet for the answer to my question, however, the results always have to do with how large of a print you can make from an xMP photo. My question is how small can individual elements on the subject be and still be discernable for an xMP camera and how does one perform this calculation?

Let me explain:

I am working on a project at work where we want to print a QR bar code on a label and ensure that it can be read by reasonable number of devices (smart phones). Obviously making the individual blocks on the QR code very large will ensure this, however, we have limited space and want to make it as small as possible. My concern is that if the blocks are too small then folks with older devices that have low MP cameras will not be able to read the bar code because the camera will not be able to see where 1 block stops and the next begins. I am being pointed to white papers that simply state 'if you make the code this big then 99% of the devices will be able to read it, if you reduce it to this size then only 75% of the devices will be able to read it.'

I would really like to be able to calculate what the size should be based upon the MP of the camera. How do I do this?


Thanks,

Ken

 

[Derrel]

Here is the article that will answer this question; well, actually it will tell you how YOU can answer it.

The Online Photographer: How Sharp Is Your Printer? How Sharp Are Your Eyes?

 

[Garbz]

The problem is not the megapixels by itself. In theory the smallest size would be 1 megapixel per datavalue. So a 0.001 mpx camera would have no problem with a 32x32 QR code.

The issue you have is lenses and the near focus distance of the device. Most phones with resolutions larger than about 4 mpx don't have the resolving power in the optics to make use of the resolution anyway.