P: PS 27.4 Image > Trap for CMYK images isn't consistent when used in Modern UI

As a workaround, you can go to Preferences > Technology Previews and uncheck ‘ Enable Modern User Interface’, then restart Photoshop This restores the correct behaviour, and although it is not a fix it should allow you to work with trap settings as expected.

Dave

I can replicate this in v27.5.0  on Windows 11.

Correct widths are :

.08mm = .00315 inches = 0.227 points = 0.945 pixels (@300ppi)). 

v27.5 incorrectly sets the trap approx 10 x wider than set in the dialogue - unless the trap width is set in pixels.

Dave
 

Mac OS 15.7.4

Mac Silicon M1

Issue first appeared in v. 27.4; still exists in updated 27.5.

Did not exist prior to 27.4; does not exist in version 26.4.1 (concurrently installed).

When using “Trap” command from Image menu and entering a trap width, trapping applied is extremely larger, by a factor of 10x or more (depending on resolution of art). This only occurs when the trap width is entered as a physical measurement (mm, points). It does not occur when entering a fixed pixel width.

Steps to repeat:

Create an image @ 300 ppi or higher, with two or more color channels. (Spot color or process.)

Create any shape (circle, etc.)

Fill one channel in that shape, Knock out the other, so the two channels meet at a hard edge.

Select both color channels.

Invoke the Trap command (Image menu).

Set the Trap width to a number of pixels (1-2 or so).

Note the width of the trap. (for illustrative purposes only)

Undo Trap.

Invoke the Trap command again, but this time set the width to 0.08 mm. (Standard offset press trapping.)
NOTE the width of the trap.

Undo again, and do the Trap again with a measurement of 0.23 points. (Equivalent of 0.08 mm.)

0.08 mm =0.00315 in or 0.22677 points

at 300 ppi around 0.945 pixels; or 1.417 pixels at 450 ppi.

Fractional widths can be entered for physical measurements but pixels are restricted to whole numbers.

We receive art at varying resolutions, but our trap widths are consistent, so we set our trap width in mm to ensure accuracy and consistentcy.

Hey, ​@vladan_1911. Welcome to the Photoshop Community. I'll help you figure this out. Based on the limited description, I’ve been unable to recreate this. Please share a video of the issue and the system info from Photoshop Help > System Info. Copy and paste it into a text document, then upload and attach it here.

Please test and confirm if Photoshop (Beta) has an issue. You can get Photoshop (Beta) from the Creative Cloud > Apps tab > Beta Apps section. 

Thanks! 
Sameer K

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