Introducton to Adobe Photoshop Real World Example

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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.

JPEG Quality 3

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.

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. Stevie saved as JPG

13KB: GIF file size is bigger. Stevie saved as GIF

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.

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