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PHASE IV-B: File Formats
(Save As...)
JPEG: A super compressed file format.
Joint Photographic Experts Group wrote the
compression standard for the JPEG file format. In the previous
section, the Improved Image was saved at JPEG Quality set
to Medium 3 as shown in the sample below.
The characteristic JPEG compression
artifact can be seen in the Improved Image. I call
the look mushy.
A higher quality setting would have reduced
the artifact but the file size would have increase.
Though the settings are numeric, they are not
absolute. The image size and characteristics interact with the JPEG
compression process. Testing is a must with JPEG.
Photoshop JPEG Descriptive Settings: A Great
Guide.
JPEG is universal but the setting indicators
are not. Photoshop has an excellent descriptive settings. The
results coincide with the description of Low, Medium, or High. Do some testing on your own and see for yourself.
- 0 to 2 are LOW, avoid if possible.
- 3 to 5 are MEDIUM, lot of web images
requires this.
- 6 to 7 are HIGH, better settings for
better quality.
- 8 to 10 are MAXIMUM, best settings to
use.
Paint Shop Pro is a small graphics
application that I use often. Unfortunately, its JPG setting method is gruesome
by comparison. Paint Shop Pro's JPEG settings range from 1 to 99
with no clue as to image quality.
I use Progressive set to Scan 3 for web
images. This allows the image to build in focus from soft, medium,
to sharp. The Scan 5 setting looks more like a down-loading error.
CompuServe GIF: Graphic Interchange
Format.
A great format for saving graphic files.
In this case, Paint Shop Pro is my application of choice for
handling GIF files. Especially the GIF transparent background
color option.
The sample Photoshop menu above has a torn
edge look. This would not have been possible without the GIF
transparent background color option.
A major draw back to the GIF format is its
limited 256 color range. Ordinarily, photographic images do not
survive such a radical color palette reduction.
I have seen some pictures reduced to a GIF
and they were quite passable. The process can require labor
intensive manual color palette manipulation.
Try it and you will learn a lot about
working with palettes.GIF animations using photo realistic images
will demand photo images to be reduced to 256 colors.
JPEG: Staggering Power.
12KB: JPEG set to Medium 5.
13KB: GIF file size is bigger.
- Full color JPEG file size is 12 KB.
- The 256 color GIF file size is 13 KB.
- The LZW compressed TIFF file size is
115 KB.
- The uncompressed TIFF file size is
232 KB.
This is only one example. An image with
differing characteristics will yield different file size
relationships.
TIFF With LZW Compression
The TIFF file format is excellent for archiving
or transferring photographic images. PC's and Mac's share TIFF files
easily. LZW is a no-loss alga rhythm so nothing is sacrificed for
file size reduction.
Regardless of the setting, JPG images suffer
from loss of data. This type of compression format is referred to
as Lossy. I do not recommend JPEG for archive purposes.
Photoshop Filters work best on high quality images.
Click Next for Buttons using a familiar
shape.
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