Resize DPI in batch

[jabodeely]

I need to resize hundreds of 12x8 images to 300 DPI.  How do I do this in batch.  I've tried to follow inst. to set the actions but I'm doing something wrong.  I don't want to change the dimensions only the resolution.  I'm using Photoshop CC 2019 on a Mac.  Thanks for any suggestions.

[Bojan Živković · Accepted solution]

You need only one step in your action. When recording action go to Image > Image Size, uncheck Resample and change Resolution to 300. If your image has 300 pixel/inch then change to smaller number prior recording step in action. Photoshop will not record step properly if you do not make real change, retyping same number may fail to record any data.

By the way, you can use Image Processor Pro https://sourceforge.net/projects/ps-scripts/files/Image%20Processor%20Pro/v3_2%20betas/ to change only Resolution without to record any action IPP has built in option for that.

[jabodeely]

Thanks for the suggestion.  I tried it and when unchecking the resample it DOES change the image size from 15+ x 10+ from the 12 x 8 as needed.  I need to keep the images at 12x8 @ 300 DPI.  Any other suggestions?

[Bojan Živković]

Perhaps you did something incorrect. Which processing option you are using? Photoshop action? Which script to batch process? Can you post screenshot with configuration inside batch dialogue?  Also plase post screenshot with action step expanded to see what is recorded.

If you are using Image Processor Pro please post screenshot of its window with configuration settings.

I have done same things many times and it can not resize image if not instructed, it just does not happen on its own.

[jabodeely]

I agree it's definately something I'm doing wrong.  I'm using Photoshop CC 2019.on a Mac Pro desktop.  I tried downloading Processor Pro but didn't have much luck.??  I've been using Photoshop since 2000 but never had to use the batch function but a few times.  It worked fine before??  So I have no idea what my issue is.  Probably just a stupid moment.  I can send the screen shots but it won't be until either mid afternoon tomorrow or later.  I have a few photoshoots I need to be on in the next few days.

Thank you for all your time and help.  I'm usually not this inept!  Maybe you could log on to me??? 

I am off to my shoot so I won't be able to respond in a timely manor.  🙂

[defaultgaj5a86cjqsl]

Thank you so much for this info. It work great for me.

[rob day]

On OSX you can use shell scripts for basic image manipulation, which should be faster than batching in Photoshop because the files don’t have to open. You might try this AppleScript, it resamples the images in a selected folder to 300ppi.

--Resamples images in the selected folder to 300ppi via sips
--Rob Day 2020

set theres to 300.0
set f to (choose folder with prompt "Select folder with images")
tell application "Finder"
	set i to (every file in f)
	repeat with x in i
		try
			set n to name of x
			set thepath to quoted form of POSIX path of (f & n as string)
			--get the file’s ppi res
			set r to do shell script ("sips -g dpiWidth " & thepath & " ; ")
			set cr to word 2 of paragraph 2 of r as real
			--get the 300ppi scale percentage 
			set s to theres / cr
			--get the current width in pixels
			set pd to do shell script ("sips -g pixelWidth " & thepath & " ; ")
			set nw to (word 2 of paragraph 2 of pd as real) * s
			--resample and resize
			do shell script ("sips --resampleWidth " & nw & " " & thepath & " ; ")
			do shell script ("sips -s dpiHeight " & theres & " -s dpiWidth " & theres & " " & thepath & " ; ")
		end try
	end repeat
end tell

[Stephen Marsh]

I use ExifTool for such tasks, it does not process image data, only the metadata so it is very fast:

exiftool -overwrite_original -Photoshop:XResolution='300' -Photoshop:DisplayedUnitsX='inches' -Photoshop:YResolution='300' -Photoshop:DisplayedUnitsY='inches' -IFD0:XResolution='300' -IFD0:YResolution='300' -IFD0:ResolutionUnit='inches' -r 'mac path/to/folder or file'

[rob day]

Hi Stephen, the OP wants to resample to 300ppi and maintain the output dimensions—the file would have new pixel dimensions. Will changing metadata do that? Wouldn’t the resample require image processing?

[Stephen Marsh]

Hi Rob, I may have misunderstood as the screenshot had resample unchecked with the request to change the resolution not the dimensions.

This will obviously retain the current pixel dimensions, however, the print dimensions will change accordingly.

You are correct, a resample is required to retain the current print dimensions and also set the resolution to 300.

[Bojan Živković]

"I don't want to change the dimensions only the resolution. " 

[Stephen Marsh]

Dimensions is obviously ambiguous. Print dimensions? Pixel dimensions?

But not both at the same time.

Resolution can also be ambiguous. A metadata value? Or the pixel width x height density?

[Bojan Živković]

Not in this context where dimensions and resolution are mentioned one after another. I think its clear.

Another proof is OP reply to my comment: "I tried it and when unchecking the resample it DOES change the image size from 15+ x 10+ from the 12 x 8 as needed. I need to keep the images at 12x8 @ 300 DPI. Any other suggestions?"

[rob day]

a resample is required to retain the current print dimensions and also set the resolution to 300.

This version would set the long output dimension to 18" and resample to 300ppi

set theres to 300.0
set ld to 18

set f to (choose folder with prompt "Select folder with images")
tell application "Finder"
	set i to (every file in f)
	repeat with x in i
		try
			set lr to ld * theres
			set n to name of x
			set thepath to quoted form of POSIX path of (f & n as string)
			
			set pw to do shell script ("sips -g pixelWidth " & thepath & " ; ")
			set w to (word 2 of paragraph 2 of pw as real)
			set ph to do shell script ("sips -g pixelHeight " & thepath & " ; ")
			set h to (word 2 of paragraph 2 of ph as real)
			
			if w is greater than h then
				do shell script ("sips --resampleWidth " & lr & " " & thepath & " ; ")
			else
				do shell script ("sips --resampleHeight " & lr & " " & thepath & " ; ")
			end if
			do shell script ("sips -s dpiHeight " & theres & " -s dpiWidth " & theres & " " & thepath & " ; ")
		end try
	end repeat
end tell

[D Fosse]

In this case the OP apparently wants 3600 pixels x 2400 pixels - or in other words, 12 x 8 inches at 300 pixels per inch.

Resolution is in fact an ambiguous term with two distinct and different meanings. Does it mean sample points per square unit (ppi), or sample points total (pixel size)?

[Bojan Živković]

You are probably right, I am missing the point from the very beginning. OP probably has 380ppi or higher and when he change to 300 it is increasing print dimension to 15+ x 10+ inches. In that case he need two steps in action: first to change resolution and second to reduce print dimensions to original 12 in longer side. That is probably reson why he has problem with batch execution, he is only reducing PPI using my suggestion.

[Bojan Živković]

It seems I missed to understand your problem. Do you have images with Resoltion greater than 300ppi? In that case you need to record additional step in action to change print dimensions on longer side to 12in what will automatically set smaller side to 8in. I am assuming that all your images are actually larger of what you need because (probably) you set print dimensions to 12 x 8 in what caused resolution to increase or you have missed point in resolution that it matters a lot when working with physical size not pixel dimensions.

If you have all images landscape then simply record additional step with Resample turned on and change Width to 12in. That is it, it will work with assumption mentioned above. If you have mixed orientation then you must record one more action which will be triggered by conditional step if image is vertical orientation. In that case, keep only step to change resolution and add conditional step to run action with single step to change either width or height depend on orientation of your image.

In case that you have all images in the same orientation then you can use easily and Image Processor Pro, just change unit to Inches, type units you need plus keep Resolution to 300.

I missed to change Resample to Automatic which will work just fine.

[PaullyJD]

@BojanRit appears that the v3.2b5 file doesn't play well with the latest Photoshop (v24.x). Is there an update, or supported software that you can point me to?

[Stephen Marsh]

@BojanRit appears that the v3.2b5 file doesn't play well with the latest Photoshop (v24.x). Is there an update, or supported software that you can point me to?

By @PaullyJD

https://sourceforge.net/projects/ps-scripts/files/Image%20Processor%20Pro/v3_2%20betas/

[PaullyJD]

@Stephen Marshyep, so that link shows v3.2b5 (release date 2016-02-03) as the latest of their releases, which works with PS/CC 2015.1.2, and we're up to PS 24.x where it doesn't seem to work

[PaullyJD]

It seems that Adobe Bridge offers this functionality, so problem solved