PDF export from InDesign is tiny

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.