By photovision/Emile (391) 
on January 31, 2006 3:46:34 PM CST
Introduction
JPEG - Joint
Photographic Experts Group
Pros:
Cons:
When to use:
TIFF - Tagged
Image File Format
Pros:
Cons:
When to use:
RAW - Unprocessed
camera image capturing data
Pros:
Cons:
When to use:
Suggestions
Digital Camera File Formats – JPEG, TIFF, RAW, DNG
Digital Camera File Formats (a summary)
By: Emile E. Kfouri
Full Article at www.humanscape.com\page5.html
Web Site www.humanscape.com
Introduction
Some photographers get so confused with all the options
available in digital photography that they forget one of the first decisions to
make – what file format to save the image in. Each one has its strengths
and weaknesses. I will summarize the pros and cons of the different formats
that are available in your digital camera and help you decide when to use them.
For a more detailed discussion of the different formats as well as some
examples of the differences please take a look at the full article at www.humanscape.com\page5.html
JPEG - Joint
Photographic Experts Group
Pros:
- File
is small which means you can fit more images in a memory card.
- Fast
saves to memory cards, which means you can take more images per second.
- Open
standard format can be universally viewed by nearly any web browser,
computer and image editing program.
- If
the image is properly lit and the exposure is properly set, the image
quality is quite good for prints similar to slide film.
- Option
to set image quality to low, medium and high to control quality of image.
High is the best image quality. (Some manufacturers use different names
for the 3 quality settings.)
Cons:
- File is reduced to an 8 bit (or higher) per channel image which can only represent 256 shades for each (red, green, blue) color.
- Image
is compressed by taking pixels of similar color and making them the same
color.
- Wrong
format for images that will be heavily manipulated in a photo editing
program.
When to use:
- Snapshots
of family and friends that will not be edited beyond simple cropping and
red eye reduction (use the high image quality setting).
- Images
sent by e-mail (use medium or low image quality setting).
- Documenting
through images like your furniture in case your home is damaged or robbed
(use high image quality setting).
- If all
the camera settings are on automatic, then chances are JPEG will be fine.
- I
suggest that you make this your default file format.
TIFF - Tagged
Image File Format
Pros:
- Open
standard format can be universally viewed by nearly any web browser,
computer and image editing program.
- No
image data is lost.
- Better
image quality than even the JPEG fine quality.
- More
tolerant of poorly exposed images – similar to print film.
- Saved at the camera’s max color bit depth, which is probably 12 bit (or higher) per channel image which can represent 4096 shades for each (red, green, blue) color. (This is only important if you are doing a lot of digital manipulation of the image ? it will not add any visible quality to the image.)
Cons:
- File size
is very large, resulting in slow saving of image between shots.
- Still
need to make sure that exposure, white balance and color saturation are
properly set because fixing these in the photo editing program will
degrade the image to a certain degree.
- Overkill
for typical snapshots or to send by e-mail.
When to use:
- If you
do not have RAW and are taking images that are important or will be
heavily worked on in a photo editing program.
- Weddings
and other once in a life time images.
- Fine
art images.
RAW - Unprocessed
camera image capturing data
Pros:
- No
loss of data between what the camera sees and what is in the file.
- Exposure
can be off by 3 stops or more and still be corrected in a photo editing
program.
- Camera
settings like white balance, color saturation, etc. can be changed post
exposure. Analogous to taking 3 slide film exposures at 1 stop over and
under metered reading.
- File
size may be smaller than TIFF.
- Saved at the camera’s max color bit depth, which is probably 12 bit (or higher) per channel image which can represent 4096 shades for each (red, green, blue) color. (This is only important if you are doing a lot of digital manipulation of the image ? it will not add any visible quality to the image.)
- Option
to save RAW and JPEG which is the best of both worlds. You get the photo
quality of RAW as well as a JPEG to quickly see what the image is.
Cons:
- Large
file size means that it can take longer to save an image to the memory
card.
- Difficult
to work with images because they need to be converted to something else
(like TIFF) before they can be easily shared and manipulated outside of
high-end photo editing programs and the camera manufactures software.
- Preparatory
file format that could become unsupported some time in the future.
When to use:
- Save
as RAW + JPEG if the option is available on your camera. The JPEG image is
just for you to quickly see what the image is before converting it or
opening it. JPEG image quality, in this case, is not that important and
low or medium quality should be more than adequate.
- Weddings
and other once in a life time images.
- Fine
art images.
Suggestions
Keep in mind that each file format has its strengths and
weaknesses. It is a good idea to think about what you are planning on doing
with the image. If it is to send to someone by e-mail or to print an 8x10 inch
image, then JPEG will be adequate. If the image is something important and will
be heavily edited in a photo editing program then select RAW (+ JPEG) if you
have that option, otherwise select TIFF. In short just use JPEG unless it is very
important.
Happy image making!
Emile Kfouri
Full Article at www.humanscape.com\page5.html
Web Site www.humanscape.com
Read 6,001 times
Reply
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From dejudicibus/Dario (1,779)
on February 1, 2006 9:46:47 AM CST
Mmm.... you said:
File is reduced to an 8 bit image which can only represent 256 colors.
As far as I know, JPEG images have 16 millions of colours, not 256. That's GIF.
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From oledk/Ole (5,383)
on February 2, 2006 4:32:11 PM CST
It's 8 bits per color channel or a total of 3*8=24 bits per pixel. I.e. 256 shades of green, 256 shades of red and 256 shades of blue. A total of 256*256*256 = 16777216 different colors.
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From photovision/Emile (391)
on February 2, 2006 7:48:02 PM CST
You are very correct. In all cases I ment to say per chanal and did not do so. I will update the article. Thank you very much for bringing this up.
Emile
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From jonudde/Jon (24)
on March 13, 2006 1:11:38 AM CST
What about JPEG-2000 standard? My camera has an option of JPEG-2000 file formats. I have no find any noticeable difference to JPEG. Pictures should be better than JPEG but on the other hand this format is not so common...
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From photovision/Emile (391)
on March 16, 2006 6:45:55 AM CST
JPEG-2000 is actually a very good image compression format based on some cutting edge mathematical algorithms. I like it a lot. The problem is that it is not well supported and it is proprietary so you usually need to buy a program that can read, view and convert the file. I just do not see it having the potential to catch on so I did not talk about it. However if it was a public file format like the regular JPEG it would replace it very quickly because it is such an improvement over regular JPEG.
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