1. As others sugges, if you have a RAW setting on your cameras, you should use that. If you don't, you should probably get one that does.

2. I'm going to disagree with the naysayers who say this is useless. You can partially defang them by pointing out that while this doesn't fully test a camera against a human eye, it is a reasonable test on its own merits and generally answers the question that people are actually asking when they ask "what's the resolution of the human eye?" (After all, the difference in capabilities goes both ways; sure, human eyes are a great deal more sensitive on many measures, but would someone please show me their eye's 10x optical zoom? (Hello to the 2040s!))

A further observation that "megapixels" is not useful would be called for, though. We're really comparing angular resolution for a certain set of settings. But we can accept "megapixels" as a slang term if we also fix certain other camera parameters to ones common to consumer cameras in the market.

3. Using eye charts is a good idea, I think. I've seen comparisons that try to compare rod density on the human eye, but that's really hard. I'd consider adding a note that standardized eye charts measure what humans can really see rather than try to compare two extremely different hardware platforms directly.

Among the many hats that I wear, one is optics designer.

A useful resolution test is to take pictures of alternating black and white bars, then use some sort of image analysis software to measure the contrast ratio, then draw a graph of contrast versus "frequency" which is inversely proportional to the spacing of the bars. You could define the resolution as the frequency or spacing where contrast drops to some arbitrary value such as 50 percent.

Contrast won't depend on light level unless the camera is doing some interesting post-processing.

It might be worthwhile to Google "USAF test chart" and look at what pops up under Images, because folks have conjured up test patterns that are useful for determining the contrast of an imaging system in one exposure.

What I think might be tricky is to come up with an objective definition of resolution or contrast that is amenable to both physical and physiological measurement.

[edited to add "inversely"]

I hate to be negative on interesting experiments, but this test is almost useless.

The noise of the sensor and the JPEG compression of the camera almost overwhelm the actual resolution in the test images. Additionally, the eye gets a larger amount of information over time during fixation, while the camera is only exposed once, with the resulting aliasing of pixels against the structure of the pattern.

Were the cameras saving raw images? Looks like JPEG artifacts are visible in some if the images.

More information about the cameras would be nice. How do their lens sizes compare to the human eye? What kind of post-processing happens in the camera (if any)? What are the characteristics of the CCDs used? Etc.

The whole experiment seemed strange. Some of the lines you said were unreadable, I could read. Also, some of the ones you said were readable, were unreadable to me. Seems pretty subjective.

Did all of the cameras tested have the same size lens? A physically large lens should have better low light performance, regardless of the # of megapixels.

Why is there a bright outline around the letters? It looks like the photos have been sharpened.