Adobe photoshop elements User Manual

ADOBE PHOTOSHOP ELEMENTS

PNG-24 format is suitable for compressing 
continuous-tone images. However, PNG-24 files 
are often much larger than JPEG files of the same 
image. PNG-24 format is recommended only 
when working with a continuous-tone image that 
includes multilevel transparency. (See “About 
PNG-24 format” on page 229.)

Choose PNG-24 for the optimization format.

Select Interlaced to create an image that displays 

low-resolution versions in a browser while the full 
image file is downloading. Interlacing can make 
downloading time seem shorter, and assures 
viewers that downloading is in progress.

If the image contains transparency, select Trans-

parency to preserve transparent pixels as trans-
parent; deselect Transparency to fill fully and 
partially transparent pixels with the Matte color. 
(See “Making transparent and matted images” on 
page 233.)

Transparency makes it possible to place a nonrect-
angular graphic object against the background of a 
Web page. Background transparency, supported 
by GIF and PNG formats, preserves transparent 
pixels in the image. These pixels allow the Web 
page background to show through in a browser. 

Background matting, supported by GIF, PNG, and 
JPEG formats, simulates transparency by filling or 
blending transparent pixels with a matte color that 
you choose to match the Web page background on 
which the image will be placed. Background 
matting works better if the Web page background 
will be a solid color, and if you know what that 
color will be.

The original image must contain transparent 
pixels in order for you to create background trans-
parency or background matting in the optimized 
image. You can create transparency when you 
create a new layer. 

Note: You can use the magic eraser tool or the 
background eraser tool to easily create transparency 
in an image. (See “Using the magic eraser tool” on 
page 140 and “Using the background eraser tool” on 
page 141.)

GIF format and PNG-8 format support one level 
of transparency—pixels can be fully transparent or 
fully opaque, but not partially transparent. 
PNG-24 format, on the other hand, supports 
multilevel transparency, letting you preserve up to 
256 levels of transparency in an image.

Open or create an image that contains 

transparency, and choose File > Save for Web. 

In the Save For Web dialog box, select GIF, 

PNG-8, or PNG-24 as the optimization format.