Tim Randles wrote:
> what is wrong with JPEG format?
>
Nothing, if you understand what it is and what it does, and use it
appropriately.
JPEG has two separate characteristics that are important:
First, it only allows 8 bits of color brightness information for each
color channel. That gives 256 separate levels of brightness per color.
That simply isn't enough to store the range of brightness that can be
captured by the sensor in your camera. That means that the processor in
the camera has to make a lot of decisions for you about how much shadow
and highlight detail to discard and how much to compress at the ends of
the brightness range.
A shot with limited brightness, like the one Bob posted, poses no
challenge to the processor, 8-bits can easily contain the image with
little or no compression. many professional photographers working in
studios where they have control over the light use JPEG. With most
outdoor shots, and especially those in sunlight, a great deal of
processing is required to get the image into JPEG.
The process is much like what automated prints from color neg film go
through to get into those prints you take home. Many, many outdoor shots
have blankish, whitish skies in those prints. Scan the film in 16 bit,
and you find nice blue skies with cloud detail in them. One can then
edit the image to retain both the people, places, etc. and the shadow
and/or highlight detail one wants in each. RAW allows you to do much the
same thing to the images from your DSLR. The details are different , but
the principle is the same.
When you shot RAW, the actual unprocessed output from the sensor is
saved in the RAW file. The process of decoding and processing it into
the desired output form is then under your control. If output to 16-bit
TIFF images, they can theoretically store over 65,000 levels of
brightness per color, more that the camera sensor can provide. So it
provides lots of room to capture everything, then adjust it to what you
want. You can then convert to 8-bit and have the image you want in a
reasonable size.
Second, JPEG provides for variable amounts of lossy image compression.
Unlike the TIFF format, for example, where compression involves no loss
of detail, but doesn't make imamages much smaller on disk, the JPEG
format, depending on the amount of compression, can result in
unnoticeable or quite crude degradation of image detail and sharpness.
The highest quality level (lowest compression) on DSLRs generally has no
noticeable efffect on image quality even at considerable enlargement.
With each step down in quality level, the size at which the image will
look good goes down.
> I use it all the time for convenience to give the pics to others,
>
Here's where the compression aspect of JPEG comes into play. The highest
quality JPEG from your camera is quite large. Even downsized, it may be
rather large for web posting and/or sending to others. Downsized and
compressed makes for suitable web images. Most images can be very nice
on the web at about 800x600 and only 90-130kb or so, even if they are
many megabytes in size at full size and quality. Some with lots of sky
or very dark areas might be smaller some with lots of fine detail,
larger, that's the nature of compression.
> I dont know how to edit pics in raw or other formats.. and dont have
> software for it, got suggestions for software?
>
I believe the E-500 comes with Oly's simple RAW converter. As somebody
pointed out, RawShooter Essentials is still available for free, and is
excellent.
Moose
==============================================
List usage info: http://www.zuikoholic.com
List nannies: olympusadmin@xxxxxxxxxx
==============================================
|