vector shape stroke in pixels in photoshop is points in illustrator

[David Cardillo, PRH]

apologizing up front for crossposting this here and the Photoshop ecosystem [https://community.adobe.com/t5/photoshop-ecosystem-bugs/vector-shape-stroke-in-pixels-in-photoshop-i... — I don't know within which program the issue lies.

I have vector shape objects in a PSD that have a fill and stroke. The stroke is set to 8 pixels in Photoshop, and I don't see a way to change that to any other units.

My issue is when I bring that file into Illustrator, all the strokes are converted to points — but the values stay the same. That is, they come in with strokes of 8 points where they were only 8 pixels (at 600 dpi) in Photoshop.

I don't see a way to set a stroke on a vector shape to a unit other than pixels. And I don't see a way to set the units on bringing the files into Illustrator so 8 px doesn't become 8 pts. My Preferences in Illustrator, Units > Stroke are set to Pixels.

I've tried doing community and support searches, but I keep getting results for "how to bring Illustrator art into Photoshop" or how to draw paths or vectors. In other words, nothing helpful.

[Monika Gause]

when I bring that file into Illustrator, all the strokes are converted to points

By @David Cardillo, PRH

Just so we can see what you are seeing: how do you do that?

[David Cardillo, PRH]

File > Open — select the PSD

when the dialog comes up, select the option to "Convert Layers to Objects."

[David Cardillo, PRH]

might have something to do with this:

the PSD in PS is over 4200 pixels wide @ 300 dpi

brought in to AI it comes in at just over 1000 pixels. (Document Raster Effects settings is 300 dpi)

the test file I just created with a 6px stroke in PS is still 6 px in AI, it's just that the file in AI is 1/4 the resolution, so that 6 px stroke is 4x thicker.

[Monika Gause]

Illustrator honors the resolution of the file you import. Looks like it doesn't translate the stroke wieght accordingly.

[David Cardillo, PRH]

but clearly it is not honoring the resolution.

I have a file that's 14", 4200 pixels @ 300 dpi in PS.

Opening that same file in AI and it's still 14" but just over 1000 pixels.

that is not the same resolution.

If I bring my 300 dpi raster artwork into AI, is it still 300 dpi?

And if AI cannot honor the stroke weight of vector objects, what exactly is it doing?

If PS can only define vector strokes in Pixels, it's a serious problem if AI cannot parse that into other measurements.

[Monika Gause]

Can you create a demo PSD file, so someone can try and reproduce this? And then post it here and/or in illustrator.uservoice.com

[David Cardillo, PRH]

this is my test file

I'd welcome anyone else trying to replicate.

PS 23.2.2

AI 26.1.0

MacOS 10.15.7 (Catalina)

Create new file in PS at 300 dpi. Note size in inches/mm and pixels.

Create vector shape with stroke. Note stroke weight.

Open PSD/TIFF in AI. Note stroke weight, size of file in inches/mm and in pixels.

[Scott Falkner]

The problem is caused, at least in part, by the fact that Ilustrrator does not support pixels as a unit. Yes, I know you can select “Pixels” on the ruler, but the units used are not true pixels. They are points, or 1/72 of an inch. Piels have no set physical size. an 8 pixel line can be 1/9 inch at 72 pixels per inch or 1/75 inch at 300 pixels per inch. Same image, same 8 pixels.

Illustrator files always have a physical size. If you draw a line one inch long in Illustrator and change units to pixels the line will be 72 pixels long. There is no way to specify resolution. This is a limitation of Illustrator and a mistake by the developers to include a unit erroneously called “pixels.”

[David Cardillo, PRH]

I'd say it's a limitation of Photoshop that a vector object has a stroke that can only be defined in pixels. There is no other measurement.

Other tools like Trap let you define an absolute measurement, not relative to resolution.

[Ton Frederiks]

Looks like if you change the resolution in Photoshop to 72 ppi while keeping the same amount of pixels (do not check Resample in Image Size), the shape size and stroke size will be the same in Illustrator.

[David Cardillo, PRH]

wow, that's an excellent discovery.

Here's an issue with merely implementing that:

I have pages for a graphic novel. There are art layers, and there are shape layers (balloons) and type layers. Our process is taking out the type and vector layers and resaving them in Illustrator. (They remain crisp vectors, not rastered, and the text stays live type in the exported PDF.)

The issue is my 14" file at 300 dpi is now 58.333" at 72. It makes it more difficult to reposition the text/vector art back on top of the raster art in the layout in ID.

anyone know a way to change the default AI resolution from 72dpi to higher?

[Ton Frederiks]

What happens looks like this:

If you place a 144 ppi Photoshop file that contains a vector shape with a 6 px stroke and you place the file as a link, Illustrator uses the resolution to display the stroke as 3 pt.

If you place the same file embedded (or use the place options to create layers), Illustrator reads the stroke weight and gives the vector a 6 px/pt stroke. Points and pixels have the same size in Illustrator, a pixel is given a size as 1/72 of an inch.

If you place the file linked, the vector will have the resolution of the file (as you can see when you zoom in) and become pixels when exported or printed.

If you place the file embedded, the vector will be scalable and resolution independent and become pixels at the resolution of the output (printer, monitor screen, image export).

To keep the best of both worlds, you could save the file in Photoshop as a Photoshop PDF, vector remains vector and pixels remain pixels. If you place the file linked in Illustrator and save the Illustrator file as PDF, your vectors will be vectors (if you embed it you will see that some tricks with clipping masks are used to keep it vector).

[David Cardillo, PRH]

Unfortunately I'm not using the PSD as placed or linked art.

I'm opening the vector shapes created in Photoshop and saving them as Illustrator AI files.

The problem is Illustrator reads Photoshop files as 72 dpi, no matter the resolution they were saved as.

This is compounded with PS being unable to create vector strokes in any unit other than pixels. 

(Seriously, who defines vector objects with pixels? The point of vectors is they're infinitely scalable, and ideally you can change the resolution of your image, and the vector shapes should remain the same appearance and size. It appears this is not the case.)

[Ton Frederiks]

What is the reason you open the vector shapes in Illustrator, are you modifying the shapes there?

[David Cardillo, PRH]

This is a graphic novel. I have images with art layers (that are being color corrected) and type and vector layers (word balloons).

In addition to ensuring the type is all 100% K only (much of it comes RGB) we want to keep the type editable, clean, sharp edges (not rastered), and remain live text through export to PDF. (Assistive devices, word counts, foreign language editions.)

Typically this works without issue with text layers. (Unless the type came from something like Procreate or Clip Studio, but that's another issue.)

I have an artist taking advantage of the vector shapes to create scalable, editable, black-only text bubbles. I want to preserve them, and not burn cutouts into the art behind them.

The type and vectors are opened in Illustrator, saved as AI files, them positioned over the art layers in an InDesign file.

This process works without issue for around 90% of the files we get. We can automate most of it, taking much of the heavy lifting off the design staff.

When issues like this come up (like 3rd-party apps using a different type engine) it throws a wrench in the works, and someone who's already done hours of work is looking at doing hours more to fix it.

[Ton Frederiks]

It is confusing, like you remarked, vector shapes can only have px as unit while type can have either pixels or points.

Photoshop will adjust the numbers for type when resolution or units changes, but does not for vector shapes:

Photoshop Example: Image resolution, 288 ppi

Type > 40 pt changes to 160 px when the units in Preferences are changed from Points to Pixels

When the image resolution is changed from 288 ppi to 72 ppi (without resampling, keeping the same number of pixels)  160 px remains 160 px

Type > 40 pt, units for Type in Preferences are points

When the image resolution is changed from 288 ppi to 72 ppi (without resampling, keeping the same number of pixels)  40 pt becomes 160 pt

Would it be better when the images are placed as links in Illustrator, the text and vector balloons created with Illustrator tools and the file saved as PDF with the linked images layer hidden?

[David Cardillo, PRH]

Hi, Tom, 

I tried your suggestion of saving the PSD as PDF. While it did retain the proper stroke weight, it converted all my text to outlines.

If these were only stroked vectors, it would be an option. In this workflow the purpose is to retain live type. (Also ensuring type and black lines are 100% K and overprinting.)

[Ton Frederiks]

Yes, this seems to be a limitation of the Illustrator import of pdf files (which could be improved in many ways). The text is still editable text when the Photoshop PDF is opened in Acrobat.

I would try images are placed as links in Illustrator, the text and vector balloons created with Illustrator tools and the file saved as PDF with the linked images layer hidden to be placed in InDesign?