Using Help
|
Contents
|
Index
Back
369
Adobe InDesign Help
Creating Adobe PDF Files
Using Help
|
Contents
|
Index
Back
369
•
Bicubic downsampling
uses a weighted average to determine pixel color, and usually
yields better results than does the simple averaging method of downsampling. Bicubic
is the slowest but most precise method, resulting in the smoothest tonal gradations.
A.
Before resampling
B.
After downsampling
C.
After subsampling
D.
After bicubic downsampling
Note:
Usually, InDesign can only downsample, not resample up. However, if the document
contains transparent objects, the flattener may be able to upsample the images. The
resolution to which the flattener upsamples or downsamples is controlled by using
flattener styles. For more information, see
“Controlling flattener settings and results using
styles” on page 294
.
Compressing and resampling images
Compression and resampling can significantly reduce the size of an Adobe PDF file, but
can also degrade image quality. However, it doesn’t affect the quality of text and line art.
You may want to experiment with these options to find an appropriate balance between
file size and image quality.
Note:
Before setting compression options, check with your service provider for recom-
mended settings.
To resample color or grayscale images:
1
Click Compression on the left side of the Export PDF dialog box.
2
For Color Bitmap Images or Grayscale Bitmap Images, choose a resampling method.
3
Enter a resolution in dots per inch (dpi) that is 1.5 to 2 times the halftone screen
frequency—the number of lines per inch (lpi) of halftone dots—at which the Adobe PDF
file will be printed or viewed.
As long as you don’t go below this recommended resolution setting, images that contain
no straight lines or geometric or repeating patterns won’t be affected by a lower
resolution. InDesign resamples all color or grayscale bitmap images in the document
above that resolution value.
Note:
InDesign has a sampling threshold of 1.5. Because of this threshold, InDesign
won’t resample an image unless the resolution of the image exceeds 1.5 times the value
specified here.
A
B
C
D