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I'm creating a new document, choosing Web profile, setting width and height equal to image size. But the image appears half as big as it really is. That is, I need to place image 4 times to fill the document. Why is that? Am I missing something?

UPD Sorry for not saying it explicitly, I'm specifying document extents in pixels, and choosing resolution 72 ppi.

UPD As for my question being marked as duplicate. The suggested question indeed clarifies that Raster Effects is not Document's Resolution, and is ignored when pasting images. When using Web profile, images are being pasted as if the document has 72 ppi. Since pixels in Illustrator was redefined as physical units, such that 1 inch = 72 pixels.

But it doesn't address my other source of confusion. And the fact to be considered when pasting images. Images, specifically png ones, can contain information about physical extents.

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First, there is no such thing as Illustrator document's ppi. It just treats pixels as physical units, such that 1 inch = 72 pixel.

Second, Raster Effects has no effect on how big Illustrator makes an image pasting it in a document.

So, if you create a document with dimensions 1920x1080 pixels, and paste an 144 ppi image of the same dimensions, it ends up taking quarter of the document. Since 1920 pixels of the image are supposed to take 1920 / 144 inches, which is 1920 / 144 * 72 = 960 = 1920 / 2 pixels.

In other words, one might say, Illustrator pastes an image as if the document has 72 ppi when document extents are given in pixels.

Third, when doing screenshots on Windows with Snipping Tool, resulting image's ppi depends on size of "text and other items". Where Smaller - 100% corresponds to 96 ppi, Medium - 125% to 120 ppi, and Larger - 150% to 144 ppi.

Fourth, you can surely check image's ppi with Photoshop. For that you need to open the image and click and hold Document Sizes in status bar. But if the image doesn't contain information about physical extents, Photoshop displays 72 ppi nevertheless.

Alternatively, you can use ImageMagick, which displays physical extents only if they are present:

$ identify -verbose img.png | grep pHYs
    png:pHYs: x_res=5669, y_res=5669, units=1
$ echo '5669 * 0.0254' | bc
143.9926
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I am assuming that you image resolution is 72ppi (because its a common resolution for images like png and jpeg).

In Illustrator when you create a new document the Default resolution of file is 300ppi. Reduce it down to 72ppi and now when you import the image file in illustrator it will perfectly fit the canvas.

enter image description here

  • Well, I didn't think png files can contain information concerning physical extents. My image resolution was 144 ppi. It was a screenshot, if anything. I used ImageMagick to find that out: $ identify -verbose img.png | grep pHYs png:pHYs: x_res=5669, y_res=5669, units=1 $ echo '5669 * 0.0254' | bc 143.9926 – x-yuri Mar 31 '16 at 11:09
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    Nothing to do with what is asked. That is just how the live raster effects happen. Illustrator has NO pixel resolution. Illustrator is a page description language one may have mixed resolutions on the page – joojaa Mar 31 '16 at 11:49
  • Can you elaborate? Why is it called Raster Effects, not Document's resolution? And how can one have mixed resolutions on the page? – x-yuri Mar 31 '16 at 18:20
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    @x-yuri because its not document resolution. Resolution only makes sense in a pixel editor where everything has a uniform resolution. Page devices are interested in size of objects, a image has a set number of pixels what its size is depends on how big you scale it inside the page description. So import 2 images and give them different scales they should now have different resolutions. Document resolution makes no sense in a vector software. – joojaa Apr 1 '16 at 7:35
  • @joojaa What is Raster Effects thing exactly then? I can only see what it affects, resulting size of the image being pasted. Maybe some other things. And I don't understand the name. – x-yuri Apr 1 '16 at 21:16
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Did you take your screenshot on retina Mac?

I'm not on a retina mac at the moment to test, but someone in this post says the retina Macs save screenshot PNGs at 144dpi.

https://apple.stackexchange.com/questions/105185/how-can-i-stop-my-retina-display-from-taking-2x-sized-screenshots

For an RGB document with pixel dimensions Illustrator sets-up the art board at screen resolution (72dpi) and the photo is placed to match the inch-size of the document.

A 144px wide image at 72dpi is 2-inches wide. A 144px wide image at 144dpi is 1-inch wide. So it's half the size when placed.

  • I did the screenshot on PIXUS Tasktab running windows 10. – x-yuri Apr 1 '16 at 21:11
  • Googling shows that your display is a high-dpi display. If Windows 10 also sets the screenshot resolution to double the default this may be your issue. Can you open the screenshot in photoshop and check the dpi? Or can you create a fresh test image set to 72dpi to see if it works better? – Mysterfxit Apr 2 '16 at 3:39
  • First, like I said, the screenshot's pixel density is 144 ppi. Believe me, ImageMagick can be trusted ;) Second, I did screenshots with Snipping Tool. Third, first thing that comes to mind when you think about windows and pixel density is 96 ppi, isn't it? And indeed, with default size of "text and other items" Snipping Tool makes 96 ppi screenshots. When setting it to 125%, it's 120 ppi now. And 150% correspond to 144 ppi. – x-yuri Apr 3 '16 at 16:04
  • Moreover, when image doesn't contain information about physical extents, Photoshop still shows 72 ppi (when I click and hold on Document Sizes in status bar). As opposed to ImageMagick. – x-yuri Apr 3 '16 at 16:52
  • Maybe I'm misunderstanding you, but if your image is 144dpi and Illustrators default RGB document is 72 dpi that seems like it may be the issue? – Mysterfxit Apr 5 '16 at 4:36

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