223
votes
Accepted
What does an unprocessed RAW file look like?
There is a tool called dcraw which reads various RAW file types and extracts pixel data from them — it's actually the original code at the very bottom of a lot of open source and even commercial RAW ...
- 144k
32
votes
Do smartphones suffer from degrees of chromatic aberration? If so, how is it possible?
Because the chromatic aberrations happen in the lens, not the sensor - the picture is already distorted by the time it reaches the sensor, so it doesn't matter if there is a Bayer matrix (or any other ...
- 22.2k
25
votes
How was photo data processed and transferred back to Earth from satellites before digital photography became commonplace?
Luna 3 did something as complicated as you thought: It took photos on a film, processed it in a kind of onboard minilab, and then scanned and radioed it back home in analog way not unlike an old fax.
...
- 2,090
23
votes
Accepted
What type of editing is necessary to achieve this type of watch photo?
To me, it is just that you dial is over-exposed, easy to fix with the Curves tool of your editor:
In other cases, just using the contrast tool could be easier, but here this would blow out the ...
- 22k
21
votes
Why does my Canon 700D take so long processing when I take a long exposure?
To reduce the processing time for long exposures, you want to turn off Long Exposure Noise Reduction. However, you may not want to give up the benefit of LENR.
Long Exposure Noise Reduction (LENR) is ...
- 176k
20
votes
How was photo data processed and transferred back to Earth from satellites before digital photography became commonplace?
Amongst the myriad online pages documenting the Viking series, here's one
which states clearly
The Viking Lander camera design was very different from vidicon
framing or CCD array cameras. The ...
- 1,887
20
votes
Accepted
Why don't cameras record light data throughout the entire shutter?
It's been done in X-rays.
The TimePix is a 256x256 detector. It has three operating modes:
the usual "total energy in this pixel since we started integrating";
Time-over-Threshold (TOT): the ...
- 316
19
votes
Accepted
Is it possible to find out what compression ratio was used for a particular JPEG?
No, you can not and it does not make sense to do so, since there is no ubiquitous definition of the JPEG compression level. The actual result when saving a JPEG with compression level 60 in one ...
- 3,388
19
votes
Why don't cameras record light data throughout the entire shutter?
You are missing some obvious problems with this idea.
You want to "continously" capture the light data, but that's already being done.
Apparently you mean to have a series of images available after ...
- 17.5k
14
votes
What does "frequency" mean in an image?
I will try to explain with the simplest math terms possible. If you want to skip the math, jump to part II, if you want to get the short answer skip to Part III
Part I
Frequency of a signal means the ...
- 282
13
votes
How can I convert an Apple iOS HEIF image into JPEG?
Support for reading HEIF was added to ImageMagick 7.0.7-22, you have to install it with --with-libheif flag.
e.g. on macOS with Homebrew: ...
- 2,279
13
votes
What does an unprocessed RAW file look like?
It's a really really big grid of numbers. Everything else is processing.
- 271
12
votes
What is the difference between HSV and CIE-Lab color space?
A perceptual uniform color space ensures that the difference between two colors (as perceived by the human eye,) is proportional to the Euclidian distance between the colors, within the given color ...
- 221
12
votes
Why don't cameras record light data throughout the entire shutter?
You suggest "Or every time a photon hits a pixel on the sensor give it a timestamp" — this would be a huge amount of data. A quick search suggests that each pixel — or sensel — in a digital camera ...
- 144k
11
votes
Is it generally accepted that "Samsung 'space zoom' moon shots are fake" and that some cellphones (e.g. S20 Ultra) use AI to add features?
Based to the article in The Verge I get actually Samsung fake the moon. Of course there are vague expressions from the company about the process and when what is in use. But my personal estimation and ...
- 12.5k
10
votes
Is it possible to find out what compression ratio was used for a particular JPEG?
You can, sort of. ImageMagicks' identify command can show a estiamte
identify -verbose image.jpeg
will produce (a lot of) ...
10
votes
Are award winning landscape images edited?
The short answer to the question is: it depends. Some award winning images are entirely shot in camera, some are enhanced in the darkroom, some are enhanced digitally.
The ultimate question here is ...
- 3,211
9
votes
Accepted
How do I correct the huge blue-shift in these images?
I'm not sure how much they can really be rescued - there's one heck of a lot of blue in there & very little of anything else.
Applying a Levels Layer & pushing the mid-point of each colour by ...
- 23.4k
9
votes
What does an unprocessed RAW file look like?
I know it's already been answered quite well by mattdm, but I just thought you might find this article interesting.
In case the link goes down, here is a summary:
The human eye is most sensitive to ...
- 99
9
votes
Accepted
How do I fix the color in this photo using Darktable to match the out-of-camera JPEG?
While darktable is an increasingly powerful piece of software, one of its rough edges is the fact that it doesn't try very hard to produce a good default "vanilla" rendering of the RAW files from the ...
- 5,414
9
votes
Accepted
It is correct to match light sources with the same color temperature?
It's roughly true that light sources with the same color temperature have the same appearance. In fact, matching light sources in this way is exactly the reason we use the Kelvin WB scale in ...
- 144k
9
votes
What type of editing is necessary to achieve this type of watch photo?
You might be surprised by how good the simple 'Auto Tone' command is in Photoshop [Image menu].
It's always worth giving it a go before getting into any more detail. Sometimes it just gets it right ...
- 23.4k
9
votes
What type of editing is necessary to achieve this type of watch photo?
I think that rather than starting from the post-processing, you should consider another lighting approach.
If you look at the images you posted as examples of what you want to achieve, they all have a ...
- 91
8
votes
Why does my Canon 700D take so long processing when I take a long exposure?
It's not actually processing for most of that extra time. It is taking a second exposure with the shutter closed, for dark frame subtraction. This removes sensor-based pattern noise. Of course, there ...
- 144k
8
votes
Why don't cameras record light data throughout the entire shutter?
What you're asking for, continuous light sampling, might be theoretically possible but practically too expensive. It might be possible to approximate it with a very high sampling rate. This could be ...
- 181
8
votes
Accepted
How to undo all changes to an edited image in RawTherapee?
Switch to the File Browser view and find your image. Right click on the little green check mark and select "Processing profile options" followed by "Clear". That will reset the sidecar file to the ...
- 5,158
8
votes
Is it common practice to apply identical processing effects to a batch of photos?
Many demosaicing applications (RawTherapee, for instance) can save the processing on a picture (aka recipe) to repeat on others. But this is typically restricted in practice to global editing (colors/...
- 22k
8
votes
What type of editing is necessary to achieve this type of watch photo?
Move your lights lower relative to the cone, or move them farther away.
The two options will have different effects... to understand them it is easier to think of it in terms of creating the ...
- 19.4k
7
votes
What does "frequency" mean in an image?
Briefly, frequency refers to the rate of change. More precisely, the frequency is the inverse of the period of the change—that is, the amount of time it takes to cycle from one brightness (or ...
- 2,265
7
votes
How can I tell exactly what changed between two images?
You can use Imagemagick command line tools.
composite imagesrc1.jpg imagesrc2.jpg -compose difference diffs.jpg
will provide the absolute value of differences ...
- 71
Only top scored, non community-wiki answers of a minimum length are eligible