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What is a file format? |
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If you look at the file name of any of your digital photos, you'll notice something like ".jpg" at the end.
That indicates the format in which your file has been saved. Although there have been several file formats
throughout the history of digital photography, only a few have become the standard. The difference between
them has to do with compression.
What is compression and how does it work? |
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Compression is how your computer or camera reduces the size of a file. The process of compressing a photo involves
removing information that you're not likely to notice with the naked eye. Subtle gradations between colours, or fine
details in the dark areas of your photo may be lost due to compression. You're unlikely to notice these changes
without strong magnification.
Which cameras offer which types of compression? |
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Most consumer point-and-shoot cameras only have one format option and that is JPEG or (denoted with the .jpg
file extension). JPEG has become the standard for most smaller cameras because it has the highest compression.
In other words, it squeezes the information from your photo into a smaller file size than other formats.
Professional DSLR cameras offer a couple more compression formats, but only for the purposes of very
specialized editing.
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Why is image quality important for file size? |
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Different resolutions produce different results. The highest quality setting is often ideal for printing and
archiving.
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Within the JPEG format, you often have even more options for controlling the quality of your photo. Consult
your camera's manual to learn how to set JPEG quality. The lowest quality setting (or the most compressed) is
best for e-mail and sharing over the Internet. The highest (the least compressed) is ideal for printing and
archiving.
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What is the downside to editing JPEGs? |
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The first image shows the original JPEG. The second image is the same file after being saved 100 times. The
file is noticeably degraded.
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One drawback to saving photos as JPEGs is that the images will degrade each time you save them. This is known
as a "lossy" type of compression. That's why it's important to save a high-quality original and then edit copies
of that file.
You can also save your JPEG as a different file type using photo editing software. The TIFF photo file format
is "lossless," meaning that no matter how many times you save the image, it will not degrade. If this format is
an option within the software you're using, it's ideal for archiving high-quality copies of your photos.
Learn more about
organizing and archiving your digital photos.
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What other file formats are there? |
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Most DSLR cameras offer photo file formats in addition to JPEG.
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Higher end DSLR and other professional-grade cameras often offer TIFF and RAW (uncompressed) file formats along
with JPEG. Each has its strengths and weaknesses depending on how photos are handled.
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RAW
This file format is best for archiving because no compression has been applied. It is the purest format
available. Every bit of information collected from a camera's sensor has been preserved.
The drawback to saving images in RAW format is that the file size can be monstrously large, easily
upwards of 30MB to 40MB per photo with today's high megapixel cameras! Professional photographers are
often the only ones with enough space to dedicate to such oversized files.
What's more, once a RAW image has been manipulated, a copy has to be saved in another form, such as a
TIFF or JPEG.
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TIFF
This file format is ideal for editing because it still retains a large amount of image information
(almost as much as RAW). TIFF is especially good for retaining colour information. TIFF gives you a
lot to work with, while being much smaller than a RAW file.
That isn't to say TIFF files are small. Depending on the resolution of your camera, you could easily end
up with TIFF files in the 4MB to 10MB range.
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