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Photoshop vs Illustrator Measuring Units

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I’ve used Photoshop for over 25 years, Illustrator for about 2 years now. I do most of my sketching in Photoshop then bring the images over to Illustrator to vectorize them using either Image Trace or drawing by hand.

I was “today years old” when I realized that pixels and points in Illustrator are not the same size as pixels and points in Photoshop.

I kept thinking my ADHD was the culprit when I continuallly felt like my images weren’t coming over from Photoshop to Ilustrator the size I expected. 

Suddenly I realized that I’m not screwing something up,  but that the way Photoshop and Illustrator uses pixels and points (measurments) are actually DIFFERENT. That leaf I drew in Photoshop and was the “right size” in Photoshop isn’t at all what I intended when I drag it into Illustrator. This doesn’t matter so much when you’re not using linework or strokes in your work (only shapes). But it matters a great deal when you are.

 Through trial and error I came to discover that the measuring units of pixels and points are equal to one another in Illustrator.

However caution needed to be used when drawing motifs in Photoshop that were meant for Illustrator.  In Photoshop, the measuring unit of POINTS is equal to the measuring units of pixels and points in Illustrator. But when both documents are created in 300 dpi, PIXELS in Photoshop is much smaller than pixels or points in illustrator. (WHAT?!)  Obviously when you’re used to working in Photoshop you typically create documents and measurements in PIXELS, not points. And therein lies the problem.

The image above shows the discrepancy. The left blue square was created in Illustrator. It is 300×300 points. The right blue square was also created in Illustrator. It is 300×300 PIXELS. They are the same size.

The left green square was created in Photoshop and imported (dragged) into Illustrator. It was created at 300 x 300 POINTS in Photoshop and as you can see it is the same size as the blue squares. 

The right green square was also created in Photoshop and imported (dragged) into Illustrator. I was created at 300 x 300 PIXELS in Photoshop. As you can see it is much smaller than the blue squares created in Illustrator.

The easiest way to remind myself that pixels in Photoshop do not equal pixels or points in Illustrator was to create a document with sample sizes for Illustrator documents, pattern swatch sizes and stroke sizes. 

Below is an example of a document I create in Illustrator and bring into Photoshop if I’m drawing motifs directly in Photoshop. I’ll put it on the bottom layer, reduce the transparency and lock it. This way I can see the size of a typical pattern swatch in Photoshop and line thickness / weight of strokes in relationship to what I drew in Illustrator. It’s not foolproof but helps keep me on track a little bit more than when I don’t use something like this as reference.

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Hi, I'm Kerry

...of Curiously Designed. This blog documents my journey as I figure out how to finally pursue a long-held dream of being a working illustrator and designer.

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