PDF export from InDesign is tiny

[T0aster7]

Hey, first forum post! Thank you everyone – reading these Q&As has been super helpful over the years!

I just exported a poster file (24"x36") and it came to 6 mb. It has an image for the background that's 160 mb. I just can't fathom how the whole file shrank to 6 mb when exporting. Any help, much appreciated. Let me know if you have clarifying questions.

I'm defiantly exporting it as a print PDF not an interactive PDF.

My background image:

[Derek Cross]

Maybe you should have definitely exported it rather than defiantly done so!

Had the image been converted to CMYK and which InDesign Acrobat PDF Preset did you select and what was the intended output?

[T0aster7]

Hmm, so true.

The image was converted to CMYK and I tried several presets. Mostly High Quality Print but I tried one of the PDF/x version and press quality. I got a range but from 6 mb to - 7.2 mb. Output for print – so normal, 300 ppi.

I don't normally create a backgrounds of this size in photoshop and then import to ID. That's it's the only thing that I can think of that is off. Over half of the background image is a single color (I wanted to avoid any issues with different programs rendering colors different), but again, that image is close to 160 mb.

[Derek Cross]

What is the output eg: desktop inkjet printer, commercial litho, screen?

If you can go back to the original and get the image in RGB it would be better if the PDF preset does the conversion to CMYK.

[rob day]

By default the PDF-X presets compress images-- if you turn off compression in the preset settings the exported PDF size will be closer to your image's file size. The amount of compression will vary depending on the image content. If as in your case, there are large areas of repeating pixels, you would expect to get more compression.

[rob day]

Over half of the background image is a single color (I wanted to avoid any issues with different programs rendering colors different), but again, that image is close to 160 mb.

The color mode of the image is not relevant in this case—an RGB image would compress to an even smaller file size because it has one less channel.

Also, there shouldn't be a problem matching colors between Photoshop and InDesign, you just need to make sure you are not embedding conflicting color profiles. If your Photoshop file is CMYK, you can either save it with no profile, or ignore the profile in InDesign by setting your Color Setting's CMYK Policy to Preserve Numbers (Ignore Linked Profiles). As long as the placed file is an image, InDesign's eyedropper will accurately sample color values from a placed file.

[rob day]

but again, that image is close to 160 mb.

Here's an extreme example of repeating pixel compression. A solid color tiff with your same pixel dimensions and no compression placed at 307mb. Exported to default PDF/X-4 high quality compression, PDF file size is at 474K.

BTW try saving your TIFF as  a PSD, PSDs usually get better compression with repeating pixels. With my example TIF saving as a PSD resulted in a 5MB file on disk.

[Dov Isaacs · Accepted solution]

This posting made my day! Virtually all complaints on this forum are about PDF files that are “too big” and this concern is about one that is “too small!” 

Based on the information provided, the image file that was placed into InDesign was a 152.6 megabyte TIFF file. InDesign doesn't indicate what type of compression, if any, that TIFF file had. Typically, TIFF files may compressed with LZW compression, ZIP compression, or no compression. Although image content-dependent, generally the best TIFF file compression is achieved with ZIP compression although that is not the default for Photoshop. But unless one has a raster image TIFF file with contents that are “vector-like” (solid background, some lines, some simple text, etc.), even with ZIP compression, a TIFF file will typically be much larger in size that the comparable file JPEG-compressed, even at the maximum quality JPEG-compression settings.

That brings us to why the PDF file is so small. By default for the typical high quality printing PDF export settings (including High Quality Print, PDF/X-1a, PDF/X-3, and the most highly recommended setting, PDF/X-4), images are compressed on export using Automatic (JPEG), Maximum Quality with downsampling to 300dpi for images at 450dpi or higher effective resolution. The image in question in at effective resolution of 300dpi and as such is not being downsampled, but it is being compressed. The Automatic (JPEG), Maximum Quality attribute means that InDesign examines the image and if vector-like, uses ZIP compression or otherwise if photo-like JPEG compression, maximum quality is used.

I strongly suspect that the image in question is very photo-like and that JPEG compression was used. Assuming that this is indeed the case, extreme compression down to 6 megabytes for the PDF file is not unreasonable. Nor will it yield quality problems.

Bottom line is that if the PDF file displays at high quality in Acrobat and prints without a question, stop worrying and enjoy! This is probably a poster child case of the technology doing what it is supposed to do!

          - Dov

PS:     Our recommendation at Adobe for best print publishing workflow practice is to keep images in their original RGB color space along with the ICC color profile and to export the PDF using the PDF/X-4 settings. This maintains print and display device independence, the highest gamut for print regardless of the actual final print device, and avoid any issues associated with transparency flattening.

[T0aster7]

Thank you everyone for chiming in!

Peace of mind + It was great to learn this