JPEG Compression Demystified

What is the best way to handle JPEG graphics in Freeway?

are a number of answers possible for this question, and the right
advice to follow depends a lot on the JPEG graphic in question.

General Advice
JPEG (which stands for Joint Photographic Experts Group) is a lossy
compression format. This means that it throws away image data in order
to save file space. The degree to which it does so is known as its
Quality in Freeway and Photoshop.

The higher the quality level
is set (in percent), the less of the image data will be removed, and
the larger the resulting file will be on disk. But it is important to
note that even at 100% quality, some image data will always be removed,
and the process is additive. If you save a JPEG over itself or to a new
file in JPEG format, you will be throwing away additional data each
time you do so, and you will also be introducing (sometimes visible)
artifacts into the final image.

In general, it is a very good
idea to only save an image to JPEG once, and that as the last possible
step after any editing or retouching, and always at the exact size and
quality you wish to use.

If you have an image in JPEG format,
and you need to use it at anything other than the original pixel
dimensions, or you need to composite it with graphic text or another
image, you should convert the JPEG to an uncompressed format before

Examples of uncompressed formats are PSD
(Photoshop), TIFF, 24-bit PNG, and EPS. TIFF can be saved in a
compressed format called TIFF-LZW, which saves quite a bit of file
size, but is not a lossy compression scheme. Every pixel will remain
intact when the TIFF is decompressed.

Freeway Pro can import all of these formats, utilizing transparency information where available.

Express can only import GIF, PNG, and JPEG graphics, and of these, only
24-bit PNG is an improvement over the JPEG original. So if you are
using Freeway Express, convert your JPEG images to PNG before editing

Digital Cameras
Many consumer digital cameras
save their images as JPEG compressed images, in order to maximize the
number of photos that can be saved in the camera’s memory. Usually, the
degree of compression used is fairly low, and there are few if any
visible artifacts.

Some cameras allow you to change this compression setting, or to save your photos as raw
or uncompressed files. This may have an impact on how quickly you can
shoot or how many images you can take, so as with anything digital,
it’s a trade-off.

In any case, after importing your JPEG-format
photos from your camera, it is a good idea to immediately save them in
an uncompressed format, so no further quality loss is suffered while
you edit them.

Web Graphics
If you have used an
application like Adobe Photoshop or ImageReady or Macromedia Fireworks
to prepare your graphics, and have saved them at the exact size,
format, and compression that you want to use them in your Web page,
then you should import them into Freeway as pass-through images. A
pass-through image appears in the Freeway interface with a blue border,
like an HTML box.

To import an image as pass-through, draw a
box on the page, import an image (File>Import, or Apple-E), and
check the “Pass-through” checkbox in the Import dialog.

images cannot be scaled, rotated, or composited with other images, only
used at their natural size. The advantage to them is that Freeway will
not alter the image data at all.

If you were to import a
pre-compressed JPEG image into a reqular Graphics box (gray border),
the output image would be compressed again, and depending on the
settings in Freeway, might actually become larger in file size (slower
to download) than the original! It would also not look as clear as the
original, even if no scaling or other transformation was applied to it,
because the minute artifacts in the compressed original would be
emphasized by the second pass through the compression algorithm.