16MP vs 24MP comparison, continued.

Started Jun 19, 2012 | Discussions thread
philbot
Contributing MemberPosts: 832
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Re: Upscaling a 16mp image to 24mp
In reply to Meshuggah, Jun 22, 2012

Meshuggah wrote:

small writing is a good way to test this, bc if you cant read it, you know its not been rendered properly. you dont need any resizing for this. if its too small to read, or if its too blurry even when viewed at 1:1, then its no good. lets imagine comparing the two cameras again. say we reach that point where one fails, and the other is still clear enough to read. no matter if its the larger or smaller MP camera, if you can see the smallest details, such as writing, then you will be able to see more in the picture.

writing is special for this kind of test bc the detail has to remain similar to how it looks in real life. our brains identify patterns of lines as writing, so we have a built in test, in our brains, for this very thing. will this allow a smaller MP camera to print as big withough becoming pixelated? no. but i dont think many of us print big enough for a 16mp camera to show pixels anyways. even if you are going to crop, all this applies.

crop a 16 and 24mp frame evenly, if you can read the writing on one and not the other, then you have an answer. if you like things bigger just for the sake of it, then go the larger MP. but id rather have a sharp clear 8mp file than a large blurry 50mp.

how do we get dpr to do this? i have no idea, but if you have two cameras such as the a77/a57, this is an easy and accurate way to test them. if i had more than one camera i would do it right now. whenever i do, i will surely post them for all to see.

The problem with newspaper print etc is you need something that gets finer and finer and finer, so either you need a special 'eye chart' kind of target, or you need to keep moving back until the camera no longer resolves the detail.. This is why they invented the industry standard resolution charts and tests.. high contrast black/white target, looking for detail extinction.. measured in lp/h..

But, getting back to using newspapers, and showing 1:1 and resolving text, DoctorXRing has already done this for some high ISO tests, this time fairly metered (exactly the same scene/lighting and same expsosure set on each camera)

Why is the A65 much better? Well, it's a well exposed shot, and if you know the context of industry standard resolution tests and how they are performed, you'd see that using black on white targets will flatter the higher MP camera..
e.g. IMATEST Resolution vs ISO for A77

Other tests done use much less light, and the lower the light, the lower the contrast, the lower the SNR, and as we know at high ISO it's all about sensor size, not pixel size ultimately..

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