Do Megapixel Cameras Provide Better Image Quality?Author: John Honovich, Published on May 19, 2009
Pixels get all the attention but image details are what is really important to video surveillance users. The more image details, the more cases that can be solved and the fewer cameras that need to be deployed to obtain that evidence.
More pixels do not guarantee more image details. And megapixel does not ensure mega details.
This is obvious when cameras have either no light (e.g., night-time darkness) or too much light (e.g., looking at the sun). In those situations, it's hard to get any image, much less an extremely detailed one.
As I conduct megapixel camera tests, it is becoming increaseingly clear that pixel count cannot be accepted as is. It's better to think of the pixel count as the pixel potential or the maximum image detail that a megapixel camera can provide. However, some cameras and many common scenarios will provide significantly lower image detail than expected by the stated pixel count.
For instance, I am seeing that high resolutions and lower resolutions deliver the same visible image details. Conceptually, this should not happen -- a 2MP image should provide much greater image details than a 1.3MP or .5MP image - but it does.
Screencast Explaining Comparison
In the 7 minute screencast below, I review my findings and demonstrate the process I used to make these comparisons. This should help you replicate the process with the actual sample images provided in the premium section.
Why This is Important
If megapixel cameras deliver less image detail than their stated resolution, this creates 2 types of risk:
- Systems may have security flaws as they are designed to a theoretical pixel level that is not met in practice, making it likely that critical evidence is not captured.
- Or systems will waste significant amounts of bandwidth. For example, if the effective image detail is the same at 800 x 600 as it is as 1600 x 1200, then users are needlessly doubling their bandwidth for no added value.
Sample Image Comparison
All the images in this test have been aggregated into a zip folder for download: Megapixel Resolution Comparison Sample Images. This folder contains images from 2 manufacturers in 3 different scenarios at 3 different resolution levels each.
Note: This report is to examine the general concept. As such, I did not disclose the specific manufacturers. As further feedback and testing is done, I will provide more details and results on specific manufacturers.
A few recommendations:
- Be careful about accepting stated resolutions for megapixel even for use in 'normal' lighting conditions. The actual image detail provided may vary significantly.
- For megapixel cameras you are already using, you may be able to lower the set resolution, save bandwidth/storage and not give up any image details/forensic capability.
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