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74 votes

Aren't all digital images ultimately just pixel values between 0 - 255?

Sorry, but your basic premise is wrong: an image can be encoded as an array of RBG pixels with 8 bits per value, but there are a lot of other ways: one channel with one bit/channel (pure black and ...
remco's user avatar
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51 votes

Aren't all digital images ultimately just pixel values between 0 - 255?

If at the core, photos are just 3 channels of pixel values [0, 255] X RBG, But photos are not "just 3 channels of pixel values" even "at the core." Computer screens are typically made up of an array ...
Caleb's user avatar
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19 votes

Aren't all digital images ultimately just pixel values between 0 - 255?

In addition to @remco's fantastic answer, I want to add why there are different codecs for (roughly) the same purpose. Codecs are designed to: Be lossless vs. lossy Encode fast vs. reduce filesize ...
flolilo's user avatar
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13 votes

Aren't all digital images ultimately just pixel values between 0 - 255?

There are several reasons why this assumption is incorrect, and they all come down to one thing: What scale are you actually using? And that can be broken down a little further: What is 255? "...
mattdm's user avatar
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10 votes

Aren't all digital images ultimately just pixel values between 0 - 255?

If at the core, photos are just 3 channels of pixel values [0, 255] X RBG That is a seriously broken assumption and the rest of your question is simply not answerable without breaking away from it. ...
Peter Green's user avatar
8 votes

Aren't all digital images ultimately just pixel values between 0 - 255?

No, an image is not just RGB values in the range 0-255. Even if you ignore storage formats, there are many ways to describe color. Here are some examples: Red, green and blue components (RGB) Cyan, ...
Fax's user avatar
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6 votes
Accepted

Why are rangefinders not directly above the lens?

Rangefinders use two "viewports" in order to get the split image to aid in focusing. If you look closely you will see the second little window usually near the lens itself. It would be possible to ...
Mike Sowsun's user avatar
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5 votes

Aren't all digital images ultimately just pixel values between 0 - 255?

Your premise is not wrong: any image can be represented using an N-dimensional array of finite values. Personally, I generalize that using discrete geometry instead of a matrix, but the essence is the ...
Fábio Dias's user avatar
5 votes
Accepted

What processing is done on RAW files in the camera?

It varies highly from camera to camera. Some designs do a minimum of processing on the image sensor itself, others do a little more. Those that do more do so mainly in the area of noise reduction ...
Michael C's user avatar
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5 votes

Longer or shorter focal length for good IQ for low light portrait photography?

"Image quality" commonly includes factors such as sharpness, resolution, distortions, aberrations, flaring, ghosting, etc. If all of these are identical between lenses, there would be no difference in ...
xiota's user avatar
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4 votes
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How close are we to the theoretic limits of sensor low-light performance?

Obviously, if we get this ratio to just "1", we'd get our perfect photon counting device, and clearly we aren't there yet, but with the commercially-available sensors in 2017, how close are we? The ...
Rob's user avatar
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4 votes
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Why are specular highlights sharp when focusing on close object?

We see and photograph objects that are mostly illuminated by reflected light. Now most surfaces are irregular, thus the light they reflect is highly diffused. However, frequently, objects have shiny ...
Alan Marcus's user avatar
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4 votes

From a user perspective, is a stopped down variable aperture zoom lens equivalent to a constant aperture zoom lens?

Typically, the constant aperture zoom would be sharper. The vast majority of lenses get sharper when stopped down, this includes constant aperture zooms and prime lenses too. So when you stop down an ...
Itai's user avatar
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4 votes

From a user perspective, is a stopped down variable aperture zoom lens equivalent to a constant aperture zoom lens?

All other things being equal, yes — mostly. In terms of exposure and depth of field, they would be as close to functionally equivalent as things get in the real world. The shape of the aperture ...
mattdm's user avatar
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4 votes

Aren't all digital images ultimately just pixel values between 0 - 255?

Bitmaps A bitmap (BMP) is essentially what you describe, an array of numbers that represent pixel colors. E.g. something like 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1 Lossless compression Now, let's ...
Brythan's user avatar
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4 votes

Aren't all digital images ultimately just pixel values between 0 - 255?

Let's say it was true, that every pixel was just three numbers (red, green and blue) each in the range 0-255. Other answerers have started by (correctly) challenging that assumption, but for ...
jez's user avatar
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3 votes

Aren't all digital images ultimately just pixel values between 0 - 255?

For RAW and TIFF formats, as far as I can tell, the answer (as others have said) is that they do not actually always use the same colour spaces (e.g. RAW files might use more bits per pixel so can ...
LangeHaare's user avatar
3 votes

Why are rangefinders not directly above the lens?

One advantage of having the viewfinder on the top left corner of the camera is that you can get your right eye very close to the viewfinder without having your nose bump against the back of the camera ...
Jules's user avatar
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3 votes

Rule of thirds -- is there any scientific proof behind it?

I’m actually writing a dissertation on this topic and the use of composition grids in general. Based on my research, there is some evidence for the rule of thirds and phi grids being aesthetically ...
Colin freeman's user avatar
3 votes

What processing is done on RAW files in the camera?

Back in the 1980s, Craig Anderton wrote a book called Home Recording for Musicians in which he observed that a recording studio isn't a capturer of reality, it's a processor of reality. You should ...
Blrfl's user avatar
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3 votes

Longer or shorter focal length for good IQ for low light portrait photography?

When imaging under feeble light conditions, need to use a large lens opening like f/2.8 or f/2 or f1.4 etc. Thus large f-number are a requisite, they capture more light. As alternatives, you can set ...
Alan Marcus's user avatar
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2 votes

When do straight lines become curved when talking about projection?

When do straight lines become curved when talking about projection? When you decide what type of projection you wish to use. A rectilinear projection will preserve straight lines (but not correct ...
Michael C's user avatar
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2 votes
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Capturing and stitching images without distortion/perspective correction given perfect control

No, this is not possible using FOV and camera rotation alone. You need to setup an oblique frustum, which is equivalent of the shift lens, used in architectural photography.
szulat's user avatar
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2 votes

Aren't all digital images ultimately just pixel values between 0 - 255?

Yes, but how you get to those 1s and 0s is very different. I will lay out an example, but it's fake and is suppose to illustrate more than be accurate. Keep in mind that all digital images are ...
coteyr's user avatar
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2 votes

Aren't all digital images ultimately just pixel values between 0 - 255?

I'll chime in with a bit of supplementary info as I've worked with image sensing and encoding/compression, albeit mostly moving images. In its basic form, an image (ANY image) displayed on a ...
John U's user avatar
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2 votes

Would there be a noticeable difference between long exposure and brighter light?

In properly exposed photographs, the only difference you (the viewer) should see is if something in the frame was in motion during the exposure. A sufficiently fast exposure will effectively freeze ...
BobT's user avatar
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2 votes
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Would there be a noticeable difference between long exposure and brighter light?

I do a lot of technical imaging and I know about image noise. You question is to the point, let me give you a to the point answer. The difference in noise will probably be small and favorable in the ...
Mecgrad's user avatar
  • 66
2 votes

luminance range for camera

When recording raw files with linear gamma encoding it requires 1 bit/EV; so if recording in 8bit (256 values) then the max range would be 8EV. However, most cameras only record in 8bit when recording ...
Steven Kersting's user avatar
2 votes
Accepted

Why doesn't a shorter shutter time cause less capture time/ readout time?

The sensor lines can be left in integration mode (turned on) for as long as necessary to make an exposure brighter or darker. But a sensor line cannot be read out and reset until the previous sensor ...
Steven Kersting's user avatar

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