Saving Images

Although JPEGView has been designed primarily as an image viewer, it also sports the ability to resave images with QuickTime previews and custom Finder icons.  In addition, JPEGView can perform the very simple conversion between the standard JFIF format and the MacintoshÕs own JPEG-compressed PICT format, allowing you to save most JPEG-compressed images in either format.


File formats in the Save dialog

When you choose the Save As item from the File menu, you are presented with a standard save file dialog, with a few extra options appended to the bottom.  Anything that looks familiar works as usual.  The remaining options allow you to choose the output file format or to include additional data with the image file.  Additionally, by checking the ÒClose when finishedÓ box, you can instruct JPEGView to immediately put away the image after it has finished saving it, thereby avoiding any long window updates that might follow.

If you are saving an image that has been compressed using JPEG, the file format popup menu will offer you several choices, allowing you to save your image in one of the three output file formats that JPEGView supports: JPEG-compressed PICT, JFIF, and PICT Resource.  More details concerning the properties of the PICT and JFIF file formats can be found in the File Formats and File Types chapter.  The oddball format available here is the PICT Resource format, which is useful mainly for saving JPEG-compressed PICT images in a useful format for programmers.

Also, please note that any PICT image which is ÒbandedÓ, that is, made up of several small JPEG images sewn together, cannot be saved as a JFIF file.  Banded PICT images are sometimes produced by QuickTime whenever memory space is low.  Since the JFIF image format was designed to store only a single image, a banded PICT cannot be converted to JFIF without decompressing the composite image and recompressing it as a single image.  JPEGView does not support this sort of functionality.

If the image you are saving has not been JPEG-compressed, then you will have to save it in its original format, and there will be no popup menu for you to choose from.  However, you will still have the luxury of choosing to add QuickTime previews and/or custom color Finder icons to the image for future ease-of-use.


Saving modified images

In addition to simply allowing you to save the image data out to a file, JPEGView also allows you to save cropping information, QuickTime preview images, custom Finder icons, and color reduction with your image.

There are two ways to get JPEGView to save the cropping information with an image.  The most straightforward is simply to crop the image in JPEGView, and then choose Save As from the File menu with the cropped image frontmost; when saved, the cropping is retained.  Alternatively, you can select the portion of the image you wish to crop to, and then issue the Save As command.  When you do this, the popup menu at the bottom of the dialog will be enabled, allowing you to tell JPEGView to ÒUse selection to crop ImageÓ.

If you have checked the ÒInclude preview (thumbnail) imageÓ box, JPEGView will create a preview image.  This preview image is simply a smaller representation of the full image, allowing you to quickly see what the image is without having to decompress the whole thing first.  QuickTime automatically supports viewing of these preview images in the Open dialog for all formats except JFIF.  The ability to view JFIF previews can be added to QuickTime by placing the JPEGView JFIF Preview extension in your Extensions folder.  See the chapter Viewing Images for more details on viewing JFIF previews.

JPEGView also supports the creation of custom icons for saved images.  This option extracts a portion of the image (selectable in the Preferences) and shrinks it down to the size of a Finder icon, adding this information to the saved file.  The resulting document will then appear in the Finder not with the standard JPEGView icons (which are pretty cool to begin with), but with this postage stamp-sized icon instead.  If you have a color system, this might enable you to guess which image you would see if you double-clicked the icon.

Sometimes it is convenient to be able to specify a smaller portion of the image from which to take the icon data.  JPEGView allows you to do this by simply selecting the subsection of the image you want, and then choosing ÒIconÓ from the ÒUse selection to crop...Ó popup menu at the bottom of the Save dialog.  This will instruct JPEGView to use the selected area of the image for the icon, while leaving the entire image intact (to crop the image as well as the icon, choose ÒImageÓ from the popup menu).

JPEGViewÕs color reduction information can also be included whenever you save a JPEG-compressed image.  What this means is that when opening this image in the future, JPEGView and certain other image viewers can detect and make use of this information without having to slog through the time-consuming color reduction.  When you open the image with JPEGView specifically, this information serves to define the Image Colors, which JPEGView will automatically use.


The final result

Once you have entered a filename and have chosen your desired options, click on the ÒSaveÓ button to perform the operation.  If you chose to create a preview or icons, a progress dialog will appear to keep you updated on the status of JPEGViewÕs work; otherwise, JPEGView will perform the save operation quickly and quietly.