How to Use Corel PhotoPaint 8 to Make Web-Friendly GIF & JPEG Images

Web Works Part 3 - JPEGs 1

JPEG Images
JPEG images are True Colour and have a 24 bit colour DEPTH (or more). That is, for each pixel, 24 bits of information are stored to describe the colour (8 for RED, 8 for GREEN, and 8 for BLUE). JPEG images can be compressed a great deal but the compression method is lossy, resulting in poor quality images at high compression ratios. See the Glossary for more information on JPEG images


Browser differences when displaying JPEGs.
Different browsers will read and display variants of the full JPEG specification to varying degrees. Old browsers (Netscape versions 2 and below and IE version 3 and below) will not display progressive JPEG images (p-JPEG). Even some new browsers will not interpret and display JPEG images compressed using OPTIMIZED compression engines (a PhotoPaint option) or those compressed using nonstandard encoding ratios. Therefore, to be safe, don't use the optimized setting or the nonstandard compression ratio options available in the JPEG Export dialog box (described below). However, as most people are now using browsers that can view progressive JPEGs, that option is fairly safe. Most web browsers currently display a variety of the JPEG specification known as JFIF.

Saving JPEGs and Layered Images.
If you have created an image with either layers or masks, these features will NOT be saved in the JPEG format. In order to retain your images in a completely editable format, save your WORKING image in Corel PhotoPaint native format (.cpt) and use Photo-Paint's Export feature (see below) to export into another format while retaining full editability

If you have completed all steps of the image creation process, you may then use File/Save As.. (from the Menu) to save the file as a JPEG with the .jpg extension (JPEG standard file extension type).

However, you may wish to just save a snapshot of the current image as a JPEG and then continue to work on it. To keep the image in the current editable format, use Photo-Paint's Export feature.

Click File/Export.. from the Menu. Then select the image type from the 'Save As Type..' drop down selector (Figure 1). The Export feature will not alter the format of the current image and will allow you to retain all objects, layers and masks.

Click the 'Save' button. You will probably see one or more warning dialogs concerning the inability to save multiple objects or masks with this format.

Click OK to to continue and close any of these pop up messages.


Figure 1:
The Export an Image to Disk Dialog box.

To export your image in the JPEG format, select 'JPEG Bitmap image' in the 'Save As Type...' dropdown selector.




The JPEG Export dialog box
The JPEG Export dialog box then appears (Figure 2).

There are many options when saving JPEG images in Corel PhotoPaint 8. There are at least 2 different compression methods, virtually an infinite compression level specification (0-100%), smoothing of the image (interpolation of colours in adjacent pixels) during compression, the ability to save the image as' progressive' (similar to interlacing for GIF images - see below), plus the ability to optimize the compression encoding process. (Refer to Figure 2).


Figure 3 depicts several of the additional user-friendly options in PhotoPaint 8's JPEG Export dialog (these are also present in many other PhotoPaint 8 dialogs too) which demonstrate some of the reasons I prefer PhotoPaint 8 for producing images for the WWW compared to other programs such as PhotoShop.

The Lock Preview icon allows the user to set up an instant preview of the current settings without the need to press the preview button. When the lock icon is depressed, a preview will occur instantly. If the lock icon is not depressed, the user needs to press the 'Preview' button.

The instant preview updates the resultant file size also. The Preview Mode toggle button to the left of the lock toggles between a single Result preview panel, and a dual panel showing both the Original and the Result images. I prefer to see both the original and the result at the same time.


Figure 2:
The JPEG Export Dialog box.

  1. JPEG Compression slider (0-100%).
  2. Smoothing Slider (0-100%).
  3. Original uncompressed file size (usually in bytes).
  4. Progressive (display when opening the image) checkbox - similar to the interlaced option for GIF images.
  5. Optimize checkbox - enables PhotoPaint to change and select an optimal encoding method (NOT recommended for use in web sites with a broad audience - test in selected browsers first).
  6. Encoding method Sub-format dropdown menu. The standard sub format is 4:2:2, the optional is 4:4:4 (Optional setting is NOT recommended for use in web sites with a broad audience - test in selected browsers first).
  7. File size of final compressed JPEG image.

Figure 3:
Additional controls on the JPEG Export dialog box.

The lock icon allows for an instant preview of the current settings, while the icon with the small computer screens toggles between a single 'results' pane and dual 'original' and 'results' panes. The Original and Result panes allow you to view the result of your compression/save settings before commitment. The preview images can be enlarged or reduced by clicking with the left (zoom in) and right mouse (zoom out) buttons. The image can also be moved (panned) within the pane by dragging the hand cursor with the left mouse button. The latter manipulations must be performed in the 'Original' pane if both the Original and Result panes are displayed.



Summary of important points when saving JPEG images using Corel PhotoPaint 8.

  • For general Web work, do NOT check the Optimized checkbox and leave the Sub Format as standard (refer above).

  • Both the Compression and Smoothing sliders may be adjusted up to the maximum if desired.

  • Note the two sets of numbers near the bottom of this dialog box. There are the size in bytes of the original image and the size in bytes of the final JPEG at the current settings.