Optimization options for JPEG format
JPEG is the standard format for compressing continuous-tone images such as photographs. Optimizing an image as a JPEG format relies on lossy compression, which selectively discards data.
Optimization panel for JPEG format
A. File format menu
B. Quality Level menu
C. Optimize menu
Quality
Choose an option from the Quality Level menu,
or specify a value in the Quality text box. The higher the Quality
setting, the more detail the compression algorithm preserves.
However, using a high Quality setting results in a larger file
size than using a low Quality setting. View the optimized image
at several quality settings to determine the best balance of quality
and file size.
You can use masks from type layers, shape layers, and alpha channels to vary the quality level across an image. This technique produces higher-quality results in critical image areas without sacrificing file size.
Optimized
Select Optimized to create an enhanced JPEG
with a slightly smaller file size. The Optimized JPEG format
is recommended for maximum file compression; however, some older
browsers do not support this feature.
Progressive
Select Progressive to create an image that
displays progressively in a Web browser. The image will display
as a series of overlays, enabling viewers to see a low-resolution
version of the image before it downloads completely.
Note: Progressive JPEGs require more RAM for viewing, and are not supported by some browsers.
Blur
Specify the amount of blur to apply to the
image. This option applies an effect identical to that of the
Gaussian Blur filter and allows the file to be compressed more,
resulting in a smaller file size. A setting of 0.1 to 0.5
is recommended.
ICC Profile
Select ICC Profile to preserve the ICC profile
of the artwork with the file. ICC profiles are used by some browsers
for color correction.
Matte
Specify a fill color for pixels that were transparent
in the original image:
- Click the Matte color swatch and select a color in the color picker.
- Choose an option from the Matte menu.
Pixels that were fully transparent in the original image are filled with the selected color, pixels that were partially transparent in the original image are blended with the selected color.
Preserve EXIF Metadata
Select to preserve metadata from a digital camera.