PDF exporting images at 244 ppi instead of 300ppi from Indesign

[yagerbomb1911]

I have just come up against a problem where I am exporting a PDF from Indesign, which is outputting the images at 244ppi, not 300ppi. The original images are at 300 ppi. I have tried all high-resolution exports from the preset menu and the export menu options All the high-resolution options have these same values for the compression. I have tried, high-quality, press quality and the PDFx1 options. I have also tried compatibility up to Acrobat 8 to no avail. Does anyone know how to fix this so I get the images coming out as 300 PPI in the pdf?

[James Gifford—NitroPress]

Where are you seeing the 244ppi value?

Are your source images 300ppi or greater in effective resolution?

[yagerbomb1911]

You can go into acrobat and using the edit function you can view the image in photoshop, that is how I saw the 244. 

[James Gifford—NitroPress]

Okay. The effective PPI of the images in the source document would still be the controlling factor here. As noted, that's displayed in InDesign's info panel when the image is selected. If it's not 300ppi or greater, that will be the export resolution.

[rob day]

Hi @yagerbomb1911 , If you check the scale of your 300ppi image it would be 123% -- resolution is resized not resampled when you scale an image in InDesign. The Export Compression tab only allows Downsampling, there is no option to upsample.

[Peter Spier]

To expand a bit on what @James Gifford—NitroPress has said, the effective PPI, (which you can set the links panel to display, as well as seeing it in the info panel for a selected image) is the actual (saved resolution in the image file) PPI times the scale factor used when placing it on your page in InDesign.  When you scale an image up on thje page its effective resolution goes down in inverse proportion. I used to demondtrate this to my classes using a checkerboard pattern drawn on a balloon. Each square represents a pixel, and as the ballooon expands the number of pixels remains constant but they get larger in size, so you have fewer of them in any given inch.

The most likely reason you are seeing 244 PPI is that you have scaled the images and that's the effective resolution.

[James Gifford—NitroPress]

And just to expand on this — PDF exports do not upscale images; the settings you show are only for downscaling to a common limit if an image exceeds a selected PPI. And banish the phrasing "300ppi image" and all its kind from your mind, as that's something of a phantom. Images have only two resolution values: the pixel width (and height), and the width placed in a layout or displayed on a screen. You get effective PPI from the intersection of the two. An image file that is 900 pixels wide, placed at three inches in the layout, will indeed result in 300ppi effective resolution. But that same image placed at six inches across will only be 150ppi effective resolution... and exporting it to PDF will leave that resolution unchanged. (If placed at one inch across, then, it would be effectively 900ppi, and the export would downsample it to 300ppi.)

But it's vague and useless to refer to "300ppi images" as any meaningful designation.