PDF Ground Controls Categories – Images
DEFINING THE PDF GROUND CONTROL CATEGORIES: IMAGES
The Images category for Portable Document Format files is in the PDF Ground Controls area in FlightCheck preflight software by Markzware.
IMAGES
Alternate:
Image workflows can be used to substitute a low-resolution image for a high-resolution image. Each image is tagged with a color space and information determining whether the image will print or not.
Alternate is Default for Printing:
Alternate images are found and set to print. In PDF/X specs, an alternate image can be found, but it must be set not to print.
Rotated:
This option locates one or more images that are rotated. Rotation can add to processing time as well as alter the quality of the image.
Skewed:
This option locates one or more images that are skewed. Skewing can add to processing time as well as alter the quality of the image.
Ink Density:
Each printing project will have an ink density amount. The calculation of adding Cyan +Magenta + Yellow + Black should not exceed its project goal. (Ex. If an image has 100% of each color, equaling a density of 400, it is much too high to dry or print properly.
Over ______-%
Type a number value to set the threshold to search for ink density above a specific limit.
ICC Profile:
One or more ICC Color Profiles are located. ICC profiles are not accepted in several PDF standards that do not invoke color management. It is best to use profiles to convert colors to CMYK. (See ICC definition in Colors)
OPI:
An image using OPI (Open Press Interface) is being used. Use this option to locate missing Hi-resolution OPI images.
Transparency:
(See Colors)
16 Bits Per Channel:
Use this option to locate one or more images with 16 bits per channel. 16 bits per channel can be used to capture an image and handle some editing options. Many Photoshop operations are not allowed in 16-bit mode (Ex. Layers).
Distortion (Notice Ground control option misspelled- Distorsion in FC6):
This option alerts if one or more images are distorted beyond the specified amount. Distortion could be rotation, skews or other methods of manipulating an image.
Over ______%
Type a threshold amount to locate distortion. (Ex. Locate all above 28%)
Image Outside Mediabox:
Use this option to alert if one or more images are found outside of the document borders. MediaBox is the layout trim size plus the medium (in most cases, paper) size. This is the largest box size–includes all Boxes.
Transfer Function:
This option alerts if one or more transfer functions have been located within the PDF. Transfer functions alter image pixel data as the file is sent to the printer. These objects are not permitted in PDF/X workflows.
ENCODING C/G
This section includes the Color and Grayscale image encoding of file formats. For PDF/X file formats, LZW compression is prohibited.
(See Pages)
ASCII Hexadecimal
ASCII Base 85
LZW
Run Length
CCITT Facsimile
DCT (JPEG)
Flate(ZIP)
JPEG2000
JBIG
Other Encoding
This option alerts if one or more non-standard encoding formats have been located.
ENCODING B & W
This section covers the Black and White image encoding of file formats. For PDF/X file formats, LZW compression is prohibited.
(See Pages)
ASCII Hexadecimal
ASCII Base 85
LZW
Run Length
CCITT Facsimile
DCT (JPEG)
Flate(ZIP)
JPEG2000
JBIG
Other Encoding: (See Encoding CG)
COLOR SPACE
(See Color Document)
ALTERNATE
(See Color Document)
RESOLUTION
The DPI (dots per inch) measures the dots on a printed page. This Ground Control only Flags “Effective Resolution”. This means that if you have an image that is originally 300 dpi and you place the image at 200% scaling, the Effective Resolution of the image is cut in half and will be 150 dpi. If you place the same 300 dpi image at 50% scaling, the Effective Resolution doubles and will be 600 dpi. If a Color or Grayscale image’s Effective Resolution is below the dpi value specified in Min Res or above the specified dpi value in Max Res, this Ground Control will trigger an alert. For example if you set Min Res to 266 and Max Res to 400, and an image has an Effective Resolution of 233 dpi, the image will be flagged as out of range. If the image has an Effective Resolution of 300 dpi, the image will not be flagged. If the image is 405 dpi the image will be flagged.
Resolution:
The effective resolutions of one or more bitmaps (two times the line screen resolution considering scaling effects) should fall between a specified range.
Min Res_____________(Dpi):
Max Res_____________(Dpi)
Type a range to search between two variables. (Ex. Min = 300 and Max = 400).
Resolution Below _____________(Dpi):
Type a number to check if the resolution is high enough for quality printing. (Ex. 150 may be the lowest resolution to accept. Web images at 72dpi will print at very low quality)
Resolution Above _____________(Dpi):
Additional resolution above the typed amount is unused and will take additional processing time. (Ex. More than 450 is excessive.)
Resolution Between:
From Res_____________(Dpi)
To Res_____________(Dpi)
Resolution falls within a range. (Ex. 300dpi to 400dpi)
Bitmap Resolution:
Bitmap or Line art should be captured at a higher resolution to keep the edges crisp and clear. A bitmap image has one channel and can use more pixels to describe the image than a color photo. A true Bitmap image (sometimes called line art) has only two colors, Black and White. These images are usually scanned in at high resolution so that the image will print without jagged edges. Many people use Bitmap images as a fake vector image, thus the higher pixel counts. For example, if the resolution of a Bitmap Tiff is too low, the final image will print with jagged edges. That is why the default values for this Ground Control are Min of 1200 dpi and Max of 2400.
Min Res_____________(Dpi):
Max Res_____________(Dpi)
Type a resolution for Bitmap images. (Min = 1200 Max = 2400).
Effective Resolution:
The resolution of an image is set during scanning or capturing of that image. Once an image is placed within a page layout it can be resized larger or smaller. The math calculated is the effective resolution. The resolution of the original image divided by the scale factor. (Ex. 300 dpi enlarged to 200% equals 150 effective dpi.) Scaling by decreasing the size can sometimes help the image. If you enlarge the scale too much you will see the image degrade.
Bitmap Resolution Below _____________:
Type an effective resolution (dpi times scale factor) to locate one or more bitmaps that fall under the specified range. (Ex. 150)
Bitmap Resolution Above _____________:
Type an effective resolution (dpi times scale factor) to locate one or more bitmaps that fall above the specified range. (Ex. 150)
Bitmap Resolution Between _____________ & ______________:
Type an effective resolution (dpi times scale factor) to locate one or more bitmaps that fall within the specified range of two variables. (Ex. Between 300-400)
