211 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 ...
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  • 140k
75 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 ...
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  • 3,113
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 ...
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35 votes
Accepted

Changing JPEG to RAW to use on Lightroom?

In my opinion, none of the other answers addresses the obvious misconception in the question: There is no use in converting a JPG (comparatively low quality) to a RAW file (high quality), because you ...
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  • 446
32 votes
Accepted

Why use JPEG instead of RAW?

Beyond the very obvious memory card requirement differences between RAW and JPEG images as noted in the question: JPEGs are compressed and typically have much smaller file sizes. For example a RAW ...
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28 votes

How do I make my image comply with the requirements of this photography competition?

"we may require the originals of the awarded photographs to be submitted by the relevant participants, with a short side of minimum 2200 pixels and bit depth of 300 dpi." and " ...
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  • 167k
20 votes

Is a JPG guaranteed to produce the same pixels?

Short Answer No, decoding is not guaranteed to always be the same. However, the differences are guaranteed to be very, very small. ISO Specifications The International Organization for ...
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  • 301
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 ...
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  • 6,307
19 votes

Changing JPEG to RAW to use on Lightroom?

In the absence of real raw files, the JPG is your "raw". Most image editors, including Lightroom, can open or import JPGs. You may choose to save in another format while editing, but do not lose or ...
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18 votes
Accepted

Is there a lossy compressed file format for 16-bit dynamic range images?

It sounds like what you're looking for is JPEG2000. It has a range of options including a 16-bit lossy compression and better compression ratios than JPEG. It hasn't been as widely adopted as hoped (...
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  • 9,430
18 votes

Can I do "back conversion" of a B&W JPEG to color?

If this image were RAW, the color would still be there. But since it is JPEG, I'm afraid not. The fact that the image is in RGB format does not help, because I'd you look, you will find that in fact ...
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  • 140k
17 votes
Accepted

Does converting image file formats affect quality?

Going from JPG (which is a lossy format) to any lossless one (like PNG) does not. Going from any format to a lossy one, yes, including JPG to JPG. It could be too little to notice, and using the same ...
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15 votes

What is a "losee file format"?

I'm 99.99% sure that this is just a typo for "lossy". I've never heard of the term "losee" and can't find it in search, either. Especially if it just appears in a review question and not in the rest ...
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15 votes

What makes RAW files difficult for manipulation?

Nothing makes raw files difficult to manipulate for someone with the right expertise and tools. It's just that there aren't many folks around who have those tools and expertise. The tools needed to ...
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  • 167k
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? "...
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13 votes

What does an unprocessed RAW file look like?

It's a really really big grid of numbers. Everything else is processing.
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12 votes
Accepted

Can RAW image files deteriorate over time?

RAW files no more deteriorate over time than a DOC file would. As long as you store them correctly (with backups of course) the file will be fine. It's true that the software that you use to process ...
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10 votes

Which has a faster write time: RAW or JPEG?

First - do you have a specific problem? The time to dump an image to the memory card varies a lot from camera to camera and the best solution for your problem is probably to try to investigate it ...
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  • 8,138
10 votes
Accepted

Which file format is recommended for black and white photographs?

Shoot in RAW, and export on whatever format you like. JPEG for example. For print it can be on TIFF. And you could export at grayscale at 16 bits. But that is only for specialized usage. For most ...
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10 votes

What makes RAW files difficult for manipulation?

A RAW file is little more than a container for the output of a camera sensor. It has to be processed into an image which gives it full color information at each pixel. As such there are no programs ...
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10 votes

How are 360° photos stored and processed?

How are 360° photos stored? Do they have a special file format or are they projected onto a regular png/jpeg? 360x180 panos are stored a number of different ways, but most commonly as a single image ...
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  • 49k
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. ...
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9 votes

Can I do "back conversion" of a B&W JPEG to color?

Unfortunately, a JPEG is a one-way, destructive process. It may be RGB, but it no longer contains the colors originally present, only those written in the B&W conversion process. If you had the ...
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9 votes

Why doesn't PNG show more detail than JPEG in a converted NASA image?

For photographic images and when a not too high level of compression is used, the loss of quality in the JPEG format is negligible and invisible. You'll pretty much only be able to notice it by ...
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9 votes

Is a JPG guaranteed to produce the same pixels?

No, you can't depend on decoded JPEG images being bit-for-bit identical. As an example, I tried viewing the image at the top of this page in two different browsers: Chrome 53.0.2785.143 and Internet ...
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  • 1,393
9 votes
Accepted

How are 360° photos stored and processed?

There are no finer details. Let us start from the beginning. A file You have a camera with a lens and the file stores what was projected on the sensor. You can change the lens, for example to a wide ...
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8 votes

Does converting RAW files to TIFF lose image quality?

The question here really resolves around what you mean by "quality", followed closely by needing to understand what RAW really is and how it relates to other image formats. On the first TIFF is ...
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  • 140k
8 votes

Why do modern DSLRs support JPEG but not lossless formats other than RAW?

Wouldn't it be useful to have a 24-bit RGB format (taking advantae of the camera's automatic processing modes)? Not really. Raw files are actually very space efficient, since they only store one ...
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  • 6,770
8 votes

Is there a lossy compressed file format for 16-bit dynamic range images?

JPEG2000, and you may also want to look at OpenEXR because it is supported by video hardware.
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  • 2,001
8 votes

Is it not ideal to save image as PNG for printing?

Yes, PNG is theoretically better than JPEG in preserving the ultimate image quality, but in practice this is the kind of exactness we don't really see, especially in print, where the physical ...
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