Reducing image file sizes
For some reason consultants that you may
use, outside of us, insist of giving you huge files on
CDs or DVDs that are way too big to email. Why? We are
guessing they want to impress you with the file size because
such file sizes are pretty much useless to you and us!
They all know how to make the file size smaller, but feel
free to send them to this page is they cant figure it out.
One of the biggest culprits stems from view photography
done using film and scanned.
Photographers that haven't switched to
digital are usually shooting on medium format cameras using
transparency film. This is drum scanned in CMYK and put
on CD. The resulting file size is huge. But today, with
digital advances, images (other than for print) need only
be RGB. Our 3D
architectural renderings, animations, photo-montage
and illustrations are all in RGB, in fact there is no other
choice creating CGI in 3D. Changing the colours of an image
from CMYK to RGB will reduce the file size immediately
and we would have to do it anyway. See the right sidebar
to read more about CMYK and RGB.
The next step is evaluating the file size,
geometrically needed. Each image is made up of pixels and
it's the number of those pixels that decides how big the
uncompressed image will be. We discourage people from reducing
the geometrical size of the image as we prefer to have
as much uncompressed data to work with. We
have a page devoted to overall image size of 3D architectural
renderings that also applies to these concepts.
Before you send the file you must apply
the greatest technique in reducing the file size – JPEG
compression. Put simply, there are different ways to save
a file and each one has a different finished file size.
For this article we will only refer to JPEG and TIFF, which
are likely to be the only ones you will come across anyway.
Both file types can be used for large images and both CMYK
and RGB. Both can store a high quality image.
TIFF (Tag Image File Format) is a high
quality way to store pictures with no loss in quality.
It is the file format of choice for high quality images
to be used in final print. It is also the way we provide
final data to our clients. But this file format isn't good
for sending information across the internet due to the
large finished file size. In reality, if you are sending
us view photography for incorporation in our 3D
architectural renderings then TIFF isn't needed.
JPEG (Joint Photographic Expert Group
- yes, we are geeks so we know what all the acronyms are)
is a file format that was originally designed for the transfer
of full colour images across networks that in today's terms
were unbearably slow. It is a technique of compressing
images to use less disk space and be easier to email or
transfer. It does this using a "lossy" technique
which converts data into much smaller, easier to handle
chunks but loses a small amount each time. A JPEG image
can be created to use a lot of compression or a little.
The more compression the more data gets lost. But a JPEG
with very little compression and maximum quality can be
a fraction of the size of a TIFF. You will find that the
difference between a TIFF and a high quality JPEG cant
be spotted by the naked eye!
So the simple summary to reducing file
sizes is to:
- Convert to RGB if it isn't already
- Save as a high-quality JPEG using minimal compression
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