Using transfer function to compensate for dot correction in film

When using a CMYK color profile, you cannot customize the dot correction settings. However, it is possible to compensate the dot correction by a mis-aligned imagesetter through a transfer function.

The transfer function compensates for dot corrections between images and film. For example, the transfer function makes 50% dots in the image print as 50% dots on the film. Similar to the dot correction curve, the transfer function can specify up to 13 values ​​along the grayscale to create a custom transfer function. Unlike the dot correction curve, the transfer function is only suitable for printing - they do not affect the image's color data.

Use the following principles to determine the best way to solve network point corrections:

If you are using a custom CMYK profile, use the dot correction settings in the custom CMYK dialog box to adjust the dot correction to match the print effect.
If you are using an ICC profile and the dot correction value does not match the printing effect, try to get a new profile with a matching value.
The transfer function is only used when the first two methods are not options.
To adjust the transfer function value:

Density values ​​are recorded using a projected densitometer on the film image with appropriate steps.
Choose File > Print Preview.
Select "Show other options" and choose "Output" from the pop-up menu.
Click the "Transfer" button.
Calculate the desired adjustment and enter the value (in percentage) in the Transfer Function dialog box.
For example, if 50% of the dots are specified and the imagesetter prints it at 58%, the halftone has an 8% dot correction. To compensate for this correction, enter 42% (50% - 8%) in the 50% text box in the Transfer Function dialog box. The imagesetter then prints the 50% of your desired dot.

When entering the transfer function value, remember the imager's density range. On a given imagesetter, a small high-gloss dot may be too small to allow ink to adhere. When a certain density level is exceeded, the shaded dot may be filled with pure black and all details of the shaded area will be lost.

Note: To preserve the transfer function of the exported EPS file, select Overwrite printer's default function in the Transfer Function dialog box, then select Include Transfer Function from the EPS Format dialog and export the file. (See Storing Files in Photoshop EPS Format (Photoshop).)

To save the current transfer function settings as default:

Hold down Alt (Windows) or Option (Mac OS), change the Store button to -> Default, and click this button.

To load the default transfer function settings:

Hold down Alt (Windows) or Option (Mac OS), change the Load button to <- "To Default" and click this button.

Electronic proof color

In traditional publishing workflows, it is often necessary to generate a printed proof of the document (sometimes called proof printing or matching printing) in order to preview the document color effect reproduced by a particular output device. In the color management workflow, the color profile indicates to the color management system how to display the preview document directly on the display (electronic proofing). In this way, you can preview on the screen the color effect of the document when it is reproduced by the specified device. You can print an electronic proof by using a desktop printer to generate a printed proof. (See Print proofs.)

Please note that the reliability of electronic proofs depends on the quality of the display, the profile of the display and output device, and the lighting conditions of the work environment.

Print proof

Print proofing (sometimes referred to as proof printing or matching printing) is a print simulation of the printing effect that is ultimately output on the press. Print proofing is usually generated on an output device that is cheaper than a printer. In recent years, the resolution of some inkjet printers is also sufficient to generate cheap print proofs.

Printed proofs:

Open the document in Photoshop.
Choose View> Proof Settings> Custom, then select the output device's profile in the Profile menu. Choose Shading Scheme from the Scheme menu. If you want to create multiple proofs on a specific output device, click Save to save the settings.
Click OK to close the Proofing Settings dialog box.
Choose File > Print Preview.
In the Print Preview dialog box, make sure Show Other Options is selected and Color Management is selected.
In the Source Space area, select Proof. "Proof Settings" should be the profile you specified.
Do one of the following in the Print Space area:
If you want to print using the factory configuration file selected by the printer driver, choose Printer Color Management from the Profile menu. Use this option if you do not have a custom profile for your printer and you want the printer driver to choose the best profile based on paper type, resolution, and so on. When you click the Print button, the Print dialog (for setting printer options) opens. On Windows, click the Properties button to access printer driver options and set color management options. On Mac OS, use the pop-up menu to access printer driver options and set color management options.
If you want to print using a custom profile, select the custom profile from the Profile menu and click the Print button. The Print dialog (for setting printer options) opens. On Windows, click the Properties button and set the printer driver options to turn off color management (these options are similar to No Color Management, Off Color Adjustment, or Off Color Management). On Mac OS, use the pop-up menu to access the printer driver options for color management and turn off color management.