This article should be read by everybody

Started Dec 12, 2013 | Discussions thread
Bruce Oudekerk
Bruce Oudekerk Veteran Member • Posts: 3,579
Re: Hard to bust the large vs small pixel myth

Nordstjernen wrote:

K E Hoffman wrote:

When I scale up.. If there is one red I a Sea of Gray.. it won't turn it into a big blog of 4 red pixels.

What if the single pixel is noisy, as noise is distributed at random? Then you might get a cleaner result with data from four pixels.

A 24 MP image from an APC of the same generation will start to get muddy when we go above ISO 6400.EVEN SCALED>... it will look much better on the FF 24MP.. same scaling.. difference? Larger pixels more signal per pixel and across the sensor vs the noise..at the pixel and across the sensor.

Now you are comparing sensors with different size, one capturing much more photons that the other one. The difference is NOT tied to pixel size, but sensor surface area and light-gathering power.

Small or large pixels - with modern sensors of THE SAME SIZE the amount of noise will be about the same. This is what the writer of the article is trying to tell you. And this is what is confirmed by test results and real world work.

Its very difficult to convince some photographers, maybe most photographers, that sensors of the same dimensions have the same amount of noise as higher resolution sensors of a similar generation. After all, they see proof with their own eyes on their screen. The problem is that they are looking at different proportions of the sensor output and that distinction either eludes them or they think it isn't important.

'In the real world', the images need to be normalized to actually judge anything. That means up or down sampling one of the images to the pixels dimensions of the other. That unfortunately introduces another variable. There is always a tradeoff between noise and both actual and perceived sharpness... and its not a trivial difference. After the resampling, sharpening and/or careful noise reduction needs to take place to even the playing field. For example. it is my contention that a 24MP APS-C image needs to be down-sampled to 16MP APS-C dimensions and slight noise reduction also needs to be applied. That step that is NOT debatable in my mind. Down sampling can increase the amount or quality of information on a per pixel basis and noise reduction decreases the information. Done carefully it will hopefully even out the gain and loss. The resultant images should approximate each other.  In practice this has proven true for me.

Of course in my scenario, all things are NOT always equal. If the noise inherent in the image is extremely low to begin with, the higher resolution image will prevail as the better image...even when both are at 16MP. Generally the differences will be very subtle and might only show up due to degradation of further post-processing but if the image is retained at 24MP, the image is easily judged better (although not as much as many think:)

I love your quote in another post; "Why trade resolution for nothing?" Its perfect.

Bruce

 Bruce Oudekerk's gear list:Bruce Oudekerk's gear list
Sony a7R II Sony Vario-Tessar T* FE 16-35mm F4 ZA OSS Sony FE 70-300mm F4.5-5.6 G OSS Sony FE 50mm F1.8 Sony FE 24-105mm F4
Post (hide subjects) Posted by
tex
Keyboard shortcuts:
FForum PPrevious NNext WNext unread UUpvote SSubscribe RReply QQuote BBookmark MMy threads
Color scheme? Blue / Yellow