In many situations, you’ll want to save a file to one of the standard graphics formats. In PhotoPlus, this is known as exporting.
Exporting an image means converting it to a specified graphic file format other than the native PhotoPlus (.spp) format. This flattens the image, removing layer information.
Only the SPP and the Photoshop PSD formats preserves image information, such as multiple layers, masks, or image map data that would be lost in conversion to another format.
The Export process itself can be carried out by using either a standard file dialog where you can specify the path, name and format of the image file, or by using an Export Optimizer where you can additionally compare export previews for multiple file formats before export.
Choose Export... from the File menu.
The Export dialog appears, with the file's current base name shown. Change the base name if desired.
To open the Export Optimizer to fine-tune export settings, click Optimizer, then click OK.
Click Save in the Export dialog.
The Export dialog includes additional options for use with web images (see Slicing images and Creating image maps).
You can also open the Export Optimizer first and (at your discretion) proceed to the exporting step after checking your settings. You can access the Export Optimizer at any time—not just at export time—to compare image quality using different settings (your settings are retained for each format).
The Export Optimizer consists
of a left-hand preview display (single, dual, or quad) and a right-hand
settings region, with additional View and Zoom buttons along the bottom
of the dialog. Dual and quad previews let you test and compare between
different export formats in each pane
Optimizer... from the File menu.
- or -
Click Export... from the File menu, and then click the Optimizer button.
From the Export Optimizer dialog, use the Options section to specify the file Format, and format-specific options such as bit depth, dithering, palette, and compression. The Size section lets you scale, stretch, or squash the image, while setting an export Quality setting (e.g., a resampling method such as Bicubic).
Review your optimized image, and when you're happy with it, click Export. The Close button will instead abort the export but save any format-specific option changes made in the dialog.
From the Export dialog, enter a file name, and choose a file format from the drop-down list. The export format and custom settings will be remembered for future exports. Click OK.
To change the display scale, click the dialog's Zoom Tool and then left-click (to zoom in), right-click (to zoom out) on the preview, or choose a zoom percentage in the lower left in the drop-down list. You can also select a specific area by dragging a marquee around an item of interest.
To display a different portion of the image, first select the dialog's Pan Tool, then drag the image in the active preview pane.
Click one of the View buttons shown below the preview pane to select Single, Double, or Quad display. The multi-pane (Double and Quad) settings allow for before-and-after comparison of export settings.
Set the preview display for either Double or Quad view.
Click one of the preview display panes to select it as the active pane.
In the Options section, choose an export format and specific settings. Each time you make a new choice, the active pane updates to show the effect of filtering using the new settings, as well as the estimated file size.
To compare settings, select a different display pane and repeat the process. The Export Optimizer lets you experiment freely and evaluate the results.
To revert back to a single pane, click Single.
Make sure the active preview pane is using the settings you want to apply to the image.
Click the dialog's Export or OK button to display the Export dialog.
The Export Optimizer saves settings for particular formats according to the most recent update in the Options section. In other words, if you have two or more preview panes displaying the same file format, the settings for the last of them you click in will be those associated with exporting in that format.
Choose Preview in Browser... from the File menu. PhotoPlus exports the image as a temporary file, then opens the file for preview in your web browser.
The JPG or JPEG (Joint Photographic Experts Group) file format, like GIF, is universally supported in web browsers. Unlike GIF, it encodes 24-bit images but, by default, is a lossy format (i.e., it discards some image information) depending on the selected Quality setting (this controls compression). This is the format of choice for full-color photographic images. For "black and white" (256-level, 8-bit grayscale) photos, it has no particular advantages over GIF.
PhotoPlus also supports the JPEG 2000 (JP2, J2K) format, which uses wavelet compression and reduces file sizes significantly better than PNG (see below) but does not support transparency. This format can store channels of data—such as ICC profiles!
For web graphics, the PNG (Portable Network Graphics) format has a number of advantages over GIF—the main ones, from an artist's perspective, being "lossless" 24-bit images and support for variable transparency. Whereas GIF supports simple binary ("on-off") transparency, PNG allows up to 254 levels of partial transparency for normal images. The image file includes an "alpha channel" that directs pixels in the foreground image to merge with those in a background image.
The extra channel lets you use antialiasing to create the illusion of smooth curves by varying pixel colors—for rounded images that look good against any background, not just against a white background. It's especially useful for the small graphics commonly used on web pages, such as bullets and fancy text. Because PNG is lossless and full color, it’s also an excellent storage format for work-in-progress.
HD Photo is a new
emerging lossless file format from Microsoft which offers more powerful
and efficient compression than other formats, supports richer colors, and
offers greater tonal detail over previous image formats. The file format
was previously known as WDP
HDP export requires Windows Imaging Component (WIC) to be installed on your computer. Windows Vista and XP Service Pack 3 (and later) will include WIC.
Tagged Image Format (TIF) is a well established and widely supported Adobe image format used in document scanning and imaging. It is a lossless image format but due to inherently large file sizes, the format is not recommended for use on the web. Its more modern use is for sharing high-resolution images across different computer environments.
The GIF (Graphics Interchange Format) file format is universally supported in web browsers for both static and animated web graphics. It's a lossless format (there's no image degradation) with excellent compression but a limitation of 256 colors. Use it for non-photographic images with sharp edges and geometrics—for example buttons, bursts, decorative elements, and text graphics. It's suitable for grayscale photos as well.
The GIF format supports "binary" transparency. That is, any portion of the image may be either fully opaque or fully transparent. Typically, GIFs use transparency to eliminate the box-shaped frame around the graphic that would otherwise be present. Thus elements with rounded edges, such as characters or shapes, preserve their contours over any background color or pattern.
The Export Optimizer provides special GIF options that help you preserve semi-transparency if you’ve employed antialiasing or feathering in your original image. The GIF format still wants "all or nothing," but you can opt to dither the alpha (transparency) channel and/or select a matte color with which semi-transparent pixels will be smoothly blended. Pixels that aren’t 100% transparent will still end up opaque, but the image will look a lot better.
Finally, GIF is a "multi-part" format, which means one file can store multiple images. That's what makes it a good candidate for use in web animations.
To make better use of the Export Optimizer, here’s a rundown of some of the options used and some suggested guidelines for different formats.
Bit depth relates to the number of colors in an exported bitmap image. In general, images with higher bit depth take up more disk space. Choose the bit depth that corresponds to the number of colors in the exported image. 32-bit and 24-bit settings preserve full color; 32-bit includes 8 extra bits for an alpha (transparency) channel and is equivalent to choosing 24-bit with Transparency switched on. 8-bit (256 colors) is the maximum supported by the GIF format. For pictures, 4-bit (16-color) and 1-bit (2-color) exports are also possible.
For HD photo and TIF: PhotoPlus exports HD Photo
files with a bit depth of 24 or 32 bits per pixel. TIF export offers 1
to 8 bits per pixel exports additionally.
(For 1, 4 or 8 bit) A color palette (no relation to a "floating" palette) is a table of color values that gets stored with any image having 256 colors or less. This could mean a BMP, GIF, PCX, or WMF image—plus quite a few more. Computer users with high-color monitors may not give it much thought, but in the realm of 256-color displays, palettes can make a great deal of difference. Windows itself reserves "slots" for its own "system" colors, and each application must "declare" a palette while the graphics system tries to ensure peaceful coexistence. When several colorful applications are in use, and you switch from one you another, you sometimes see the ghastly result of palettes clashing as neither application wants to relinquish its hold on a scarce system resource.
To avoid that kind of calamity when displaying web pages, the most common browsers use the same Web-safe palette of 216 colors to display images. You may be interested to know that the Web-safe palette is based on RGB values that are either 0, or divisible by 51. Permissible values are in the series 0, 51, 102, 153, 204, 255. So, for example, the RGB definition "0,102,51" would be a safe web color, while "0,102,52" would not.
If you're exporting at 256 colors or less, and web display is not an issue, there's no question you should choose the Optimized setting—as a quick side-by-side comparison in the preview window will always confirm. The program will always do a better job when it's allowed to select a range of color values that best match those in the 24-bit version, rather than having to apply the same 216 colors every time.
(For 1, 4 or 8 bit) Dithering of the digital kind (not to be confused with "showing flustered excitement or fear") comes into play with images being reduced to 256 colors or less. It's a method of approximating colors outside the actual image palette—for example, by alternating pixels of red and blue from within the palette to produce the visual impression of a purple color that's not in the palette. Applications (including web browsers) use dithering in 256-color mode if the images being displayed include colors outside the application palette. This can degrade solid-color areas and is one of the main reasons to export Web-bound images using the Web-safe palette.
When you're exporting to 256 colors or less, PhotoPlus lets you choose whether or not to use dithering. If you have an image with few colors, and preserving areas of solid color is essential, you should opt for no dithering—and the export filter will pick "nearest-match" color values from the palette being applied. You may see some color shifting, but the solid color areas will be preserved. For photographic images, on the other hand, dithering is clearly the best choice. With the "optimized palette" option, you can choose either ordered or error diffusion dithering. The former produces a discernably patterned effect, while the latter tends to average away the patterns for a more natural result.
When exporting to the 256-color
.GIF format, PhotoPlus includes an option
that lets you select a method of dithering the alpha (transparency) channel
separately from the image’s color
information. This produces a kind of scattered "see-through"
effect that may improve your results, depending how you intend to use
the final image.
Compression schemes, which apply different algorithms to encode the image information with fewer total bits and bytes, are used in many formats. With some, like BMP and TIF, the Export Optimizer gives you a choice of compression scheme. In general, use the default setting unless you know for a fact that some other scheme is called for.
The .JPG format, widely used for photographs
(and detailed in Image formats for the web), is unusual in that you can
set the level of quality desired using a slider. As you might expect,
the highest-quality setting uses least compression, with no loss of image
quality but the largest file size. The lowest-quality setting applies
maximum compression for smallest size, but yields rather poor quality.
With the aid of the Export Optimizer, you can judge for yourself—but another
factor to keep in mind is the number of times you expect to be re-exporting
a particular image. A photograph may look fine the first time you export
it at JPG level 6, but after several such saves, you'll really see the
quality loss. As a rule, keep images in the native SPP format, or export
them with the JPG's export Lossless check
box checked (or use another lossless compression scheme), until it's time
for the final export.
(JPG and Microsoft HD Photo only): You can set the export quality level using a slider. The highest-quality setting uses least compression, with no loss of image quality, but produces the largest file size. The lowest-quality setting applies maximum compression for smallest size, but yields rather poor quality.
GIF files support single-level (on/off) transparency, such that if you check Transparent and export as a GIF, any "checkerboard" regions of your graphic (those with no pixels or 0% opacity) will turn into transparent regions in the GIF; all other regions will become opaque. When exporting as a full-color PNG (32 bit), full gradations of transparency in your original design are preserved. PhotoPlus also provides Dithering options (for GIFs and 8-bit-or-less PNGs) which are similar to, but separate from, those for image colors. Dithering in regions of partial transparency causes certain pixels to drop out in a patterned way. These tiny dropouts allow underlying colors to show through, achieving smoother blends in these regions despite the limitation of single-level transparency.
The .PNG format, like GIF, is "lossless,"
but offers improved transparency support using up to 254 levels of partial
transparency for "alpha blending" effects. 32-bit PNGs use 8
bits as an "alpha channel" that directs pixels in the foreground
image to merge with those in a background image. This seamless anti-aliasing
creates the illusion of smooth curves by varying pixel colors—for rounded images that
look good against any background, not just against a specific color. Because
it's lossless and full color,
it's also an excellent storage format for work-in-progress. To preserve
gradations of transparency in your original design, check Transparency
and export as a PNG.
Leave Anti-aliased checked to preserve
edge smoothness, or uncheck the box for sharp edges, which are sometimes
(GIF only) Check Interlaced
to use an image format that will display "progressively" in
a browser: first a low-quality image will display, followed by an improved
image as the complete GIF is loaded.
Check this option and click the color sample to choose a color with which
semi-transparent pixels will be smoothly blended.
JPG only. Check this option to export as truly lossless and uncompressed, primarily for storing in-progress work in a JPEG, rather than a proprietary, lossless format (like SPP) without losing any image quality. The Quality slider is grayed out.