B4Print.com

Prinergy ColorMatch converts image objects with identical CMYK tints differently on the same page, causing visible artifacts

Symptoms

When different image objects that are on the same page and that have the same CMYK tint are ColorMatched in Prinergy, they can be converted to different tints. Visible artifacts can be created where these objects touch each other.

This problem can be encountered when using Ink Optimizing Solution (IOS) ICC DeviceLinks (DVLs) with CMYK images at the time of Refining.

Product

All versions of Kodak Prinergy software.

Cause

The problem is caused by the use of JPEG compression. The default Export Adobe PDF selection for Adobe InDesign software (and other Adobe programs) is to compress images using JPEG when flattening or saving out the PDF. InDesign uses a different JPEG encoder than Prinergy, and when Prinergy decodes the compressed image in order to apply ColorMatching, certain pixel values are rounded off and create different CMYK values than other non-JPEG areas.

Solution

Ask the originator to change the Compression settings in the Export Adobe PDF dialog box in InDesign (and other Adobe products). The settings for Color Images and Grayscale Images should be changed from the default JPEG encoding to ZIP compression.

[attachimg=1 width=400]

Workarounds

If it is impossible to get the original InDesign (or other creative application) documents and re-export them with ZIP compression, try the following workarounds:

• (Recommended) Use Enfocus PitStop Pro software to change the compression of all JPEG images in the PDF to ZIP.
• (Use with Caution) If the user does not have PitStop Pro, open the PDF in Adobe Acrobat Pro software and use File > Save As Other > Optimized PDF to force downsampling of all images to change the compression of images from JPEG to ZIP. For instance, to trigger downsampling, set the target resolution to "300 dpi or greater" and resample to 299 dpi. This method can be problematic, as there will be some loss of resolution, and the user will also have to confirm that the resolution of each JPEG-compressed image in the file is higher than the target resolution, or re-compression will not be triggered for those images and they will remain as JPEG.

Note: Callas PreFlight+ software prior to Prinergy 8.0 cannot be used as a workaround. Although PreFlight+ has an action to recompress JPEG images as ZIP, Callas prior to Prinergy 8.0 used a different JPEG decoder than Adobe and decompressing/recompressing the images in PreFlight+ will result in different ColorMatch conversions. PreFlight+ in Prinergy 8.0 and later can be used to recompress images as .zip.

Extremely thorough, well done!

Brilliant. Thank you Joe

I received this notice from Kodak too, here is the original Kodak Partner Place link:

https://services.kodak.com/app/answers/detail/a_id/71331

I posted the whole article for those that do not have access to the link.

(Edit: or for those that do not get the email notifications.)