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so I have this image that is 612x408px (300dpi?):

enter image description here

I create a new file in AI at 612x408px (72ppi) and when I import the image, the image imports in lower dimensions:

enter image description here

  1. When I scale the image up to the artboard size of 612x408, the image doesn't lose quality, so it's definitely a 612x408 of at least 72ppi (maybe even the 300). Basically just scaled down for no reason, yet having the original quality of the linked file.

  2. When I change the resolution in document raster settings, nothing changes.

  3. Also Pixel preview doesn't change anything.

Why is the imported image scaled down and not imported in its 100% size?

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  • The underlying problem is that you can not have a pixel as a unit. Pixel is a quantity, like say bananas. But bananas is a bad length unit since you can have different length bananas. Same applies to pixels. So its entirely possible to have three or four different definition of pixels in a page description language.
    – joojaa
    Apr 29, 2021 at 5:37

1 Answer 1

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It's because the image is set to 300dpi. I can see it in the image properties you posted. It's easy to fix.

  1. Open the raster image in Photoshop, do Image > Image Size, then change the resolution to 72ppi, with the resampling option unchecked, and then resave it. It's important not to resample, otherwise you will change the number of pixels.

  2. Now place the image in Illustrator on an artboard with the same pixel dimensions, and it will match the size.

Here's an example. This is a 1400px x 700px AI document, with a 1400px x 700px image at 72ppi.

enter image description here

If you are wondering why this happens, it's because Illustrator uses the PPI setting as a scale factor when placing raster images. Illustrator is a vector image editor primarily designed for use in print. In print documents, it's important that an image with a 300dpi setting is placed at the correct physical size, otherwise it will not print at the correct quality.

So, with that in mind, if you do some simple arithmetic you can see exactly why the problem is happening.

Let's say you have an AI document like my example which is 1400px x 700px. All Illustrator documents are 72ppi, this is a default that cannot be changed*. Here's how you work out the physical dimensions of the AI document

1400/72 = 19.44" and 700/72 = 9.72"

Now if we have a raster image with the same pixel dimensions, but set at 300dpi, you can work out the physical dimensions

1400/300 = 4.66" and 700/300 = 2.33"

As you can see, although the raster image is the same size as the AI document, it will be considerably smaller when placed in Illustrator, since Illustrator will scale the image using the ppi/dpi setting.

*Note: You can't change the document resolution in Illustrator. It's always 72ppi. What you changed was only the setting for Illustrator's "raster effects". I realize this can be confusing, but you must remember that Illustrator is a vector image editor, and technically vector documents have no resolution as such. 72ppi is Adobe's quirky way of saying a document has no resolution.

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    Thank you, figured it might be something with the dpi, but I expected a higher dpi image to be imported larger rather than smaller in a lower dpi document. Something here is very counter intuitive for me. Thanks for the elaboration
    – Smelis
    Apr 28, 2021 at 22:09
  • @Smelis - ah, yes I see. It's totally counter intuitive, like most things in Adobe's world!
    – Billy Kerr
    Apr 28, 2021 at 22:13
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    @Smelis - also note that PPI/DPI is confusing anyway. It might be worthwhile checking out this old article, but still very relevant: The Myth of DPI. It's quite difficult to get your head round. Essentially PPI/DPI is not the resolution of a raster image. Once you understand that, your intuition will totally change!
    – Billy Kerr
    Apr 28, 2021 at 22:23
  • @BillyKerr its because its one per unit, not unit per time (which people lump it to). DPI wouldnt be so confusing if people wouldn't on the whole ignore math and the underlying system.
    – joojaa
    Apr 29, 2021 at 5:34

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