ZePrA | Apply Photoshop color corrections to PDF files

Apply Photoshop color corrections to PDF files

In some applications it is not possible to use measurement based DeviceLink profiles. This is true, for example, if a customer brings print data and a print that should be as accurate as possible in the production run without a correct proof. If you view the print data on a monitor with a soft proof of the print standard for the production run, clear deviations from the print that you have brought with you can become visible.

In this case you could either print outside the standard and try to recreate the default – either by making gradation corrections in ZePrA or by using the capabilities of the printing press – or print inside the standard by applying Photoshop corrections to the PDF file. The latter has the advantage that you can proof the color-corrected data according to the standard and have it approved by the customer. This procedure requires an experienced Photoshop user and CoPrA’s Editing tool.

For a test with production data the demo version of the programs can also be used. To do this, meaningful objects must be combined from the existing PDF data into one file in Photoshop and combined with CoPrA’s test chart (EditTarget). This test file is then corrected under softproof conditions on the monitor. The edited image is imported into CoPrA and the corrections are taken into account in the created DeviceLink profile.

Then the DeviceLink profile can be used in ZePrA to correct the color of the original PDF data. If necessary, the corrections can be approved by the customer on a proof before printing. The printer can work as usual according to standard and reach the proof reliably.

The individual steps are described in detail in the chapter How to create DeviceLink profiles with edited charts in the CoPrA Help.

ColorLogic’s Printer Profile PSOcoatedv3_GCR_ColorLogic.ICC explained

PSOcoatedv3_GCR_ColorLogic.ICC profile

ColorLogic’s Printer Profile ‘PSOcoatedv3_GCR_ColorLogic.ICC’ explained

PSOcoated_v3_GCR_ColorLogic vs. PSOcoated_v3

Tutorial: ColorLogic’s Printer Profile ‘PSOcoatedv3_GCR_ColorLogic.ICC’ explained


Optimized Printability for neutral Image Areas

This profile is an alternative to the ICC profile ‘PSOcoated_v3‘ from the ECI. It is based on FOGRA51 characterization data and offers optimized printability for neutral image areas.

Details on PSOcoatedv3_GCR_ColorLogic.ICC

Good printability in offset printing requires optimized GCR settings (Gray Component Replacement) and a fine-tuned balance of K and CMY in separated images. When RGB images are converted to CMYK using ICC profiles the GCR settings are fixed in the CMYK printer profile and specified during ICC profile generation.

The example below shows a comparison between the GCR settings of the ECI profile ‘PSOcoated_v3.ICC’ and ColorLogic’s alternative profile:

The two main differences in regard of GCR settings of our ICC profile ‘PSOcoated_v3_GCR_ColorLogic‘ and the ‘PSOcoated_v3‘ profile from the ECI are:

1) Neutral images are printed more stable: Maximum GCR in neutrals

The original ECI profile features a medium GCR which is similar in both neutrals and skin tones. In contrast, ColorLogic’s profile has a maximum GCR in neutrals but is reduced in tertiary colors like skin tones. This GCR strategy combines the best of both worlds: A maximum GCR for neutral colors to prevent color casts as far as possible or unstable gray balances during printing. A medium GCR for skin tones to prevent grayish skin tones in case black is printed too strong.

2) More stable printability for light image areas: Black starts at zero

When using ColorLogic’s profile, black starts at zero and replaces similar CMY values. This stabilizes areas of light neutral colors. RGB images which contain neutral vignettes or drop shadows from gray to white will be printed more stable.

Links and Downloads

 

ColorLogic’s PSOcoatedv3_GCR_ColorLogic.ICC Profile

ColorLogic's PSOcoatedv3_GCR_ColorLogic.ICC

Optimized printability for neutral image areas

This profile is an alternative to the ICC profile PSOcoated_v3 from ECI. It is based on FOGRA51 characterization data and offers optimized printability for neutral image areas.

Why use ColorLogic’s version?

Good printability in offset printing requires optimized GCR settings (Gray Component Replacement) and a fine-tuned balance of K and CMY in separated images. When RGB images are converted to CMYK using ICC profiles the GCR settings are fixed in the CMYK printer profile and specified during ICC profile generation.

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GCR settings of the ECI profile ‘PSOcoated_v3.ICC’ vs. ColorLogic’s PSOcoated_v3_GCR_ColorLogic profile

The two major differences in the GCR settings:

1) Neutral images are printed more stable: Maximum GCR in neutrals

The original ECI profile features a medium GCR which is similar in both neutrals and skin tones. In contrast, ColorLogic’s profile has a maximum GCR in neutrals but is reduced in tertiary colors like skin tones. This GCR strategy combines the best of both worlds: A maximum GCR for neutral colors to prevent color casts as far as possible or unstable gray balances during printing. A medium GCR for skin tones that prevents grayish skin tones if the black is too strong.

2) More stable printability for light image areas: Black starts at zero

When using ColorLogic’s profile black starts immediately at zero and replaces similar CMY values. This stabilizes areas of light neutral colors. RGB images which contain neutral vignettes or drop shadows from gray to white will be printed more stable.

Links and Downloads

Information on Roman16 Images for the evaluation of color management workflows