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I am wondering what a "losee file format is". I came across the term in my photography class book The exact question in the book is:

Which of these file formats are considered losee?

Does that refer to a lossy compression method, or is that something else?

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    And just to be sure, actually spelled "losee"? – mattdm Jan 18 '16 at 4:31
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    Definitely spelled right. It appears in a question 'Which of these file formats are considered losee?' – jlars62 Jan 18 '16 at 5:00
  • Does the book's glossary or index have the term "losee", and do they also have the term "lossy"? In the chapter where the book talks about file formats, does it use either term consistently, or is one of the terms absent? – scottbb Jan 18 '16 at 14:16
  • @jlars62 What book are you using? – Caleb Jan 18 '16 at 14:58
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    vtc b/c This question is about an uncommon spelling error in a homework question that only incidentally relates to photography. – xiota Aug 2 at 3:52
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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 of the text — it's probably just an error.

A lossy format, of course, is one which discards (hopefully mostly imperceptible) information in order to achieve a smaller size.

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It looks like the term losee is most likely a typo, but for what it is worth, here is the answer that I ended up discovering. The possible file formats were

  • jpeg
  • tiff
  • psd
  • dng

And the answer was jpeg.

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    Just for fun, note that it's possible for JPEG to be lossless, and possible for TIFF to contain lossy images. These are not normal cases, though. – mattdm Jan 18 '16 at 21:16
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As you know, digital images are a paint-by-numbers system. This is binary math using only two digits, the zero (0) and the one (1). The word digit is Latin for finger, and its root comes from the fact that we often count using our digits. The bottom line is: a digital image file can contain a googolplex of digits. How nice it would be if we could figure out a scheme to whittle down a file for storage to save space and then reconstitute it with little or no loss of data!

Data compression to the rescue: If you wanted to condense a book, you could have everyone agree to a scheme, you could cast out all the filler words like “basically” “like” ”you know” and conjunctions like “and” but” also” “thus” “however” etc. This scheme could substitute a number or a character for each so you could later reassemble the book. Think about how much space could be saved if books were condensed this way. This is the idea behind digital file compression. The scheme can be expanded to cast out mundane repetition --- like expanses of blue sky or water. The scheme will work if everybody agrees on the rules that govern the compression and reconstruction.

One widely used scheme is under the auspices of the Joint Photographic Experts Group abbreviated JPEG. This is a “lossy” scheme that permanently casts out redundant information. The scheme attempts to do this in a way that the missing data will not be noticed. This is called “lossy” file compression.

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    All true, but the question is explicitly about "losee" compression, not "lossy" compression. – Philip Kendall Jan 18 '16 at 17:13
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"Lossy" refers to lossy compression. The most significant format using this is JPEG.

Lossy compression is a slight misnomer. What actually happens in JPEG conversion is that the data is slightly modified to facilitate better compression. The actual compression of the modified data is not, itself, lossy ( typically it's Huffman encoding ).

The modifications to the data are designed to be visually least significant. Even zoomed in it can be quite hard to spot the subtle difference between an uncompressed original and a very compressed JPEG.

The thought of using "lossy" formats tends to petrify some amateurs ( and the occasional pro ), but it really isn't a significant issue for any expect the most extreme pixel peepers.

There is a lossless version of JPEG ( called JPEG2000 ), but this is not widely used outside the medical and some scientific professions ( where any loss is unacceptable ). Unfortunately cameras and mobile devices and most software do not generally support JPEG2000.

  • The question isn't about what a lossy file format is, but what a "losee" format is. – Philip Kendall Jan 18 '16 at 11:39
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    Even allowing for Philip's comment what remains is also incorrect in a number of ways, actually data IS discarded in the process of being "slightly modified". Also JPEG2000 is not lossless, it has a lossless option but is not inherently lossless in the same way that PNG is. TIFF is similar in that you can have anywhere from completely lossless to group 3 fax, which is not renowned for image fidelity... – James Snell Jan 18 '16 at 14:16
  • I've never met anyone who is petrified by lossy compression. I know lots of people who avoid it because applying a lossy algorithm to compress an image multiple times can lead to real image degradation. People who spend $thousands on cameras and lenses to get a sharp image don't mind spending $tens on memory cards to maintain image quality. – Caleb Jan 18 '16 at 14:53
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    Also, JPEG 2000 is not the lossless form of JPEG. JPEG 2000 is a separate format altogether. It's based on wavelets rather than discreet cosine transforms, and was intended by its designers to replace the JPEG format. The original JPEG standard does include a lossless version, but it is often not implemented in JPEG encoders and decoders. – user1118321 Jan 18 '16 at 16:02
  • FWIW, while "petrified" might be an overstatement, I've definitely heard/seen/read people who I'd call superstitious about it. – mattdm Jan 19 '16 at 16:09

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