Resolution
Resolution of color or grayscale image is below
Determines whether any color or grayscale images in the PDF file have a lower resolution than the value that you specify. To change the resolution, type a value in the adjacent box. The default is 150 dpi.
Resolution of color or grayscale image is above
Determines whether any color or grayscale images in the PDF file have a higher resolution than the value that you specify. The default is 300 dpi.
To reduce the resolution, select the Fix check box, type a number in the adjacent box, and select one of the following settings:
- Average downsampling to average the pixels in a sample area and replace the entire area with average pixel color at the specified resolution.
- Bicubic downsampling to use a weighted average to determine pixel color. This usually yields better results than the simple averaging method of downsampling. Bicubic is the slowest but most precise method, resulting in the smoothest tonal gradations.
Resolution of B&W images is below
Determines whether any black-and-white images in the PDF file have a lower resolution than the value that you specify. To change the resolution, type a value in the adjacent box. The default is 1200 dpi.
Resolution of B&W images is above
Determines whether any black-and-white images in the PDF file have a higher resolution than the value that you specify. To change the resolution, type a value in the adjacent box. The default is 2400 dpi.
Kodak alternate <list> defined for images
Determines whether a Kodak alternate image is defined for images. An alternate image is used when creating low resolution PDFs from Publish to PDF File, or Vector output from Prinergy, or InSite Prepress Portal.
- To detect whether alternate images are present, select Kodak alternate <is> defined for images.
- To add alternate images if they aren't present, select Kodak alternate <is not> defined for images and then select the Fix check box.
Image has alternates defined
PDF Preflight detects whether the PDF file contains alternate images for printing.
If you want to use an alternate image, select the And one of the alternates is the default for printing check box.
Files contain CEPS data
Determines whether the PDF file contains any CEPS (CT/LW) or TIFF/IT files.
If you select the Files contain CEPS data check box, PDF Preflight marks the CT/LW data so that it is not trapped and overprint settings are not modified. Trapping CT/LW data may produce artifacts such as hairline gaps on the refined PDF. Changing overprint settings may create a result that was not intended, such as removing existing traps.
Select this check box for pages on which the content is mixed. For example, the content may have vector text and CEPS format images.
Image uses 16 bits per channel
PDF Preflight detects whether the PDF file contains any images that use 16 bits per sample.
Position
Image is rotated at an angle that is not a multiple of 90 degrees
Determines whether the PDF file contains an image that is rotated at an angle that is not a multiple of 90 degrees.
Image is skewed
Determines whether the PDF file contains an image that has a skew transformation applied. Ripping a skewed image from a PostScript format into a raster (or bitmap format) can be very time- and memory-intensive.
Image is flipped horizontally
Determines whether the PDF file contains an image that has been transformed into a mirror image.
Image is not scaled proportionally
Determines whether the PDF file contains an image in which the X scaling differs from the Y scaling.
To specify how much the X scaling can differ from the Y scaling, select the Option check box and type a number in the adjacent box. For example, if you select the Option check box and type 0.5%, PDF Preflight only detects images in which the X scaling differs from the Y scaling by more than 0.5%.
Compression
Color or grayscale images
Determines whether the PDF file contains images that are compressed using one or more of the on-screen options. From the Options menu, select one of the following options:
- JPEG compressed. JPEG compression removes image data and may reduce image quality. It can achieve much smaller file sizes than ZIP compression.
- JPEG2000 compressed. JPEG2000 compression may remove image data and may reduce image quality. It can achieve much smaller file sizes than ZIP compression.
Note: If an image is compressed with JPEG2000 compression and you modify it in Prinergy (for example, downsampling or color matching the image), Prinergy will not be able to encode it back to JPEG2000 compression. Therefore, it is recommended to select this check box, so that these images are detected, and then select the Fix check box and select ZIP (preferred) or JPEG as an alternative compression type.
- ZIP compressed. ZIP compression works well with large areas of single colors or repeating patterns, such as screenshots and simple images.
- LZW compressed. LZW compression is used in GIF and TIFF files. It is also suitable for compressing text files.
- Run Length compressed. Run Length compression does not remove data to reduce the file size, so it doesn't affect the quality of images. It produces the best results in images that contain large areas of solid white or black.
- Not compressed
To use another compression method for color or grayscale images, select the Fix check box and select JPEG or ZIP. If you select JPEG, select a level of quality from the adjacent list.
Black and white images are
Determines whether the PDF file contains black-and-white images that are compressed using one or more of the following methods of the on-screen options. From the Options menu, select one of the following options:
- JBIG compressed. JBIG compression of bilevel images uses only one bit to express the color value of each pixel. JBIG compression does not remove data to reduce the file size, so it doesn't affect the quality of images.
- CCITT compressed. CCITT compression is appropriate for black-and-white images created in paint programs and for images scanned with an image depth of 1 bit. It does not remove data to reduce the file size, so it doesn't affect the quality of images.
- ZIP compressed
- LZW compressed
- RunLength compressed
- Not compressed
To use another compression method for black-and-white images, select the Fix check box and select CCITT, ZIP, or RunLength. CCITT G4 is a general-purpose option that produces good compression for most types of monochrome images.
JPEG compression ratio
Detects JPEG images in the PDF file that may have deteriorated because of a high compression ratio. PDF Preflight looks for images with a higher compression ratio than the value that you specify. The default value is 4.