Photoshop / Illustrator / InDesign - placed image different dimensions and resolution

Question

The same problem over and over again - why do images placed in Id/Ai show different size than in PS?

I've made image in PS of about 2000x1500 pixels at 300 PPI.

Then made Ai document of 2500x1600 pixels at 300 PPI. To avoid any conversion/compression surprises I simply placed the Ps document in Ai document. Guess what? It's shrunk and terribly pixelated though MB size in link properties seems correct. Ok, then maybe for some reason it reduced the resolution: let's make an Ai doc at 72 PPI. Surprise again - the placed PS doc is exactly the same size as it was in 300 PPI doc. And exactly the same pixelated.

Let's try Id then: one with print intent (so it should have like 300 PPI) and one with web intent (should have about 72 PPI), both size like before. Guess what? Absolutely no change - Ps doc is shrunk and pixelated (and appears same size in both cases), though shows correct MB size, Actual PPI = Effective PPI = 300 and correct dimensions according to link description.

When tried with *.png file instead of Ps, nothing changed as well.

I'm totally dumbstruck by now. How is it that suddenly one 300 PPI file is not working with other 300 PPI file and 2000pix height becomes less than 1/5 of 2500pix height?...

Answer 1

There is no document ppi setting for illustrator. There is just a target setting for continious rasterisation. Neither illustrator nor indesign have a seting for the resolution of the document as it would be meaningless. Doing so would make no sense.

The source of your your confusion is using pixels as a measure of distance. Both indesign and illustrator operate on physical units. That is inches, meters, millimeters or so the size of a picture is based on whatever physical units it gets converted to.

But some people use illustrator to design pixels. So they added a pixel unit. Since a pixel has no dimension you get into a unsolvable problem. A system based on physical imaging mode can not set a size for nothing. The way the pragmatic engineers used to solve the problem was to redefine pixels as physical units. The decided that one pixel is one point.

This explains it all 300/72 is about 4.

TL;DR

Simply its not possible to set the ppi of a illustrator document. Thus source of the confusion.

Answer 2

Just adding to Joojaa's answer because it might not be so easy to understand:

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The ppi setting in Illustrator is used as a default when you rasterize effects or stuff you created IN Illustrator that will need to be rasterized. But Illustrator doesn't really care about the ppi, it cares about "real" units like the metric and imperial units (e.g. centimeters, inches, etc.)

So your 2000 x 1500 pixels = 6.667 x 5 inches @ 300ppi in reality.

but

Illustrator ignores the ppi you've set in the document setup and makes the artboard at 72ppi when you use pixels as units... so you end up with a document that is 27.778 x 20.833 inches (your 2000 x 1500 pixels @ 72ppi!)

In other words: Use the imperial or metric units when you need to work with resolution in Illustrator or InDesign, and use these dimensions when you create a new file in one of these software! Keep the pixels for web design.

Answer 3

Joojaa and go-meek have already given good answers; I will just add a bit of illustration to show you how things may not be as confusing as you think.

As go-meek has said, a Photoshop document that is 2000 x 1500 pixels at 300 ppi has (in metric units because all this imperial nonsense confuses me) an actual size of 169.3 x 127 mm. To illustrate this, open your 2000 x 1500 px document. Make sure you have your rulers on (View → Rulers or Cmd/Ctrl + R). You should see that the document is indeed 2000 x 1500 pixels in size.

If you now go to Photoshop settings → Units and rulers and set your ruler units to millimetres instead of pixels, you will instead see this:

See how it now says the document is a size that fits with the 169.3 x 127 mm given above?

(Yes, I know—I should have been an artist with such mastery of shapes and colours.)

Now, for simplicity, create an Illustrator document at the same size: 2000 x 1500 pixels (the raster resolution doesn’t matter, as the others have mentioned). Turn on your rulers (View → Rulers → Show rulers) and you’ll see that the size still fits. Now go to File → Document Setup (Cmd+Alt+P or Ctrl+Alt+P) and change Units from pixels to millimetres. You should now see more or less this:

As you can see, the Illustrator document has a completely different size from the Photoshop document—it’s about 708 x 553 mm, slightly more than four times the size of the Photoshop document. The reason why this is so is as Joojaa says: it’s basically an arbitrary decision made to somehow make pixels a physical unit.

If you place the Photoshop document into this Illustrator document, things start to make sense:

As you can see, the placed document takes up about 169.3 x 127 mm of the 708 x 553 mm document, and sanity is at least somewhat restored.

Answer 4

i had the same issue myself, and wasted almost an hour to resolve this!

when exporting an image in PS it should be 'as legacy' (meaning = for web):

go to File > Export > Export Preferences > mark option 'Use Legacy "Export As".

another option to to this in PS (without changing the settings): File > Export > Save for Web (Legacy).

once you do that, you can import it to AI. the picture will be shown in it's actual size.

Hope this was helpful!