There are two means of saving files using ProJPEG™. The first is using the ‘Save as...’ command in Photoshop and the second is ‘Save’ or command - S. You should be very familiar with save and save as from within Photoshop and using ProJPEG™ works in much the same way as saving in other formats from Photoshop.
If you perform a ‘Save as...’ you first see Photoshop’s put file dialog where you select the format to use and supply the name for the new file. Once you hit the ‘Save’ button in that dialog the options dialog for ProJPEG™ will appear.
In the options dialog for ProJPEG™ you will need to make the desired settings for compression. Minimally you should adjust the quality slider to the desired level and check or uncheck the progressive option as desired before hitting the ‘OK’ button to complete the saving process. You may also cancel at any time from the options dialog without saving the file.
Once you hit the ‘OK’ button from the options dialog ProJPEG™ begins to save the file to disk. You may also cancel saving from the progress dialog at any time before ProJPEG™ completes saving the file to disk.
Command - S saving requires no special user action and no options need be set when saving an image in the normal course of working. With ProJPEG™ it is not recommended that you ‘save’ an existing JPEG file immediately after opening it without first performing a ‘save as’ to ensure the compression setting are what you expect them to be.
Unlike, Adobe’s JPEG, ProJPEG™ does not store compression settings in the file. This means that if you ‘Save’ immediately after opening an existing JPEG file before you ‘Save as...’ and manually reset the compression options the file will be saved with the default settings of ProJPEG™ and not necessarily the settings previously used to save the file.
It is not good practice to use JPEG as a working format because of it’s lossy nature, but it is safe to edit JPEG files and resave them when necessary if done with caution. When saving multiple times in the same editing session cumulative quality loss does not occur, since the original RGB data is recompressed each time you save from the open file.
Optimizing JPEG images for the web with ProJPEG‚Ñ¢
You should limit your use of JPEG for web graphics to continuous tone, full color or greyscale images of photographic nature. These are the types of images where JPEG excels. Also, you should never save images that have been color reduced to 256 or less colors as JPEG files. Doing so will be very detrimental to image quality and also compression efficiency.
Besides those general rules of thumb, there are no practical manual optimizations that can be performed on your image prior to saving as JPEG to improve compression or quality. The final outcome will be largely dependent on the settings used to create the JPEG file.
One thing to remember when you create graphics for the web is that fast download times are often more critical than image quality. The goal is to find a mid point between both extremes that allows for the smallest possible file while maintaining acceptable image quality, with what is acceptable image quality varying by the specific use of the image. For example, a photographers portfolio would require much higher quality images than thumbnail images for an on-line catalog to achieve the desired effectiveness.
 
WELL SUITED FOR JPEG
 
NOT WELL SUITED
FOR JPEG
The live image compression preview in ProJPEG‚Ñ¢ allows you to have immediate feedback on how changing setting will affect quality and compression and will allow you to safely push compression to the limit to quickly achieve the smallest, best looking files possible.
ProJPEG‚Ñ¢ 2.1 is Copyright 1996 BoxTop Software, Inc. All rights reserved. ProJPEG‚Ñ¢ is a Trade Mark of BoxTop Software, Inc.
