Photoshop vs Indesign Resolution differences

[user2022]

To the Adobe Forum / experts

My agency have found a discrepancy that we can't understand or explain, where the resolution / dimenstions for certain images in Photoshop differ to Indesign. Our understanding is that they should match. 

Further info - we were provided with this image by the client who received it from a photographer. We have compared this to other images and have found this discrepancy to be present in some, but not the majority.

This has raised questions and we would like to understand why there is a difference if anyone can please explain it would be much appreciated!!

Dimensions provided below. For client confidentiality we cannot share the image in question. 

 

[c.pfaffenbichler]

You seem to be overlooking the Resolution. 

Also using px as unit of width in Indesign does not seem sensible (when working for print at least). 

[user2022]

We switched from mm to pixels in order to showcase the number differences. 

[c.pfaffenbichler]

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@user2022 wrote:

We switched from mm to pixels in order to showcase the number differences. 

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But that is irrelevant. 

The important thing is whether a pixel image’s effective resolution meets the ultimate output requirements. 

[c.pfaffenbichler · Accepted solution]

In any case: What matters is an image’s Effective Resolution. 

Check that in the Info Panel or the Links Panel or via Preflight. 

In this case the image has 5369px width and 300ppi Resolution. 

So when placed with 100% scaling in Indesign that results in the meaningless display of 1288,56px width – 5369 * 72 / 300  

[user2022]

Can you explain why other images return the exact same pixel dimensions between the two programs when shown at 100% in indesign?

Why is there a difference in the pixels in Indesign for this image?

[c.pfaffenbichler]

Again: Resolution. 

[user2022]

Thank you, I think that does make sense. The comparison image we were looking at was at 72 pixels / inch in Photoshop and returned the same pixel dimensions in Indesign, is that what it should be?

The reason this has been explored is due to the photographer saying that they have provided an image at 5369px width and 300ppi Resolution which should meet our requirements for sizing, however the image is much smaller when dropped into Indesign --> 1288px width.

[c.pfaffenbichler]

The width and length of an image are NOT its resolution. 

The resolution is the number of pixels per unit of length, so in Photoshop the Resolution is indicated in the Image Size dialog as px per inch or pixel per cm. 

Using px as length measurement unit in Indesign only makes sense if the intended output is a pixel image with a resolution of 72ppi. 

If an image has 300ppi resolution and the output of the Indesign document is not intended for print but for pixel output at 72ppi then one can scale the image up 416,667% and still get 72ppi Effective Resolution. 

[Derek Cross]

To add to c.pfaffenbichler's excellent explanation – a simple way to consider resolution and print size is to divide the PPI by the image pixel dimensions. So a  5369px x 6158px image would print at an optimum size of around 18" x 21" (so probably wants reducing in size).

[user2022]

Thank you this has clarified a lot and we now have a better understanding, cheers

[jane-e]

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@user2022 wrote:

My agency have found a discrepancy that we can't understand or explain,

 

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It appears you have the Frame selected and not the image. Click the "doughnut" or double-click the image to select the image and not the frame. What do you see here now?

~ Jane

[user2022]

Thank you Jane-e - but it's the same result regardless of frame / internal image. 

 

[c.pfaffenbichler]

posting overlap 

[user2022]

It was dropped in at 100% - no scaling

[c.pfaffenbichler]

Please check the Resolution/Actual PPI of the images. 

[Test Screen Name]

To emphasise, everything looks exactly right and correct. The only error is using the width/height measuring tool - the one you highlighted in red - since it doesn't actually give you an image size in pixels. Yes, this is very confusing, and I would like to see it removed, but no doubt people would complain! But the correct size is given in the image dimensions (without any unit, just 5369 x 7158).

[user2022]

Thank you, this is very helpful!

[rob day · Accepted solution]

Why is there a difference in the pixels in Indesign for this image?

Hi @user2022, InDesign has a Pixel Ruler unit that measures as a static 1/72" and has nothing to do with image resolution—an InDesign page is a vector object and has no resolution.

The Pixel Ruler unit is only useful when you are designing for screens and need to easily export a page or selecton to an image format at a specified pixel dimension. For example a document page setup as 1024px x 768px (14.2222 in x 10.6667 in) can be easily exported as a matching 1024 x 768 pixel JPEG image by setting the JPEG Export Resolution to 72ppi.

In your example the selected frame is measuring 1288.56 x 1717.92 px because you have your ruler units set to Pixels—if you set them to Inches the selection would measure as 17.8967 in x 23.86 in. An image contained in that frame can have any print output resolution, which is listed as the Effective Res in the Links panel.