Image file resizing for print output

[camelbreath]

It has been my practice to save an image in my resource folders for indesign at 100% as they come from the camera and processed in Photoshop. Then I save a 100% copy of the image with a suffix of - use, which is the one I place in InDesign. That way if I need to resize several time in production, it's not etched in stone until the final approved document.

When I get ready to output the document for press, I go to the document select the image it by clicking the center circle and copy the placed width. Then I open the file in Photoshop from the links panel, invoke the size dialog box, paste the width, click, resize, run my sharpen action, and save.

Finally, I package the document with properly resized image files. It's kind of an OCD procdure, but it has worked for me for years with documents with 20 to 30 images or so. If I have to go back and make any major image revisions, I always have a 100% original ready.

Now I am working on a book with more than 300 300-dpi images, all saved from a camera, no stock photos, so the originals are all similar in dimensions. I am prepared to do my normal procedure to ensure an accurate document but am wondering if there may be a script or program that might automate this procedure.

The client on this book is really insistent on proper resizing.

Thanks to those who know more than me,
Joe

[Eugene Tyson]

Is there really a need to do this - or are you're adding a massive amount of work that is not necessary?

Place your files from the 100% size source.

And export your PDF choose your compression settings. 

That should be about it. Is there a reason for this, are they colour managed images or images that require sharpening every time you print them for different reasons? 

300 PPI is a faux number too - it only really applies to lithographic printing - where 300DPI is derived from the LPI output of the device - which for a lot of Lithographic printers would be about 150. For newspapers, this number is lower and for high-end coffee table books, etc. the number is as high as 175 or even 200. 

The LPI is important as a lot of people multiply by 2 to get the required DPI of their images - which for 150 typical print would be 300 - but the x2 number is erroneous. It should be 1.41 - which for a 150LPI would require a DPI of 210 - not 300. 

1.41 is because a halftone square is rotated 45 degrees and measured from tip to tip - which is always 1.41. 

So if a square is 1 x 1 - the diagonal between the corners is always 1.41

 For me - place the images at the original size- no changes - and control the compression and colour conversions directly from InDesign.

If you really need to sharpen all your images all the time - can you not sharpen just the original image and save that as an optimised sharpened image?

Forgive me if your workflow requires retouching images for a specific control reason.

[Peter Spier]

I used to work that way as well (and a Photoshop action might be the way to go to speed things up). I wouldn't do more than Eugene suggests now except for a museum catalog or fine art coffee table book printed at a very high screen value.

You might have to reprocess a severe size reduction, but in general full-size images that have been properly processed export just fine.

[Robert Tkaczyk]

To add to the others - as long as you DON'T switch off resampling settings in the PDF Export profile - InDesign will automatically resample all your graphics so there is really no need for the extra work.

And even if you would include all the data from your images - you won't get better results - finer details - as the printer have limited resolution anyway - and people who will have to process your files ... well ... I wouldn't want to meet them face to face if I were you 😉

[camelbreath]

Robert, I had no idea about the resampling. Thanks for the info.

Joe