Kenny Loc: Oregon

I have a large number of images at 300 dpi that I would like to convert to 72 dpi without changing anything else. Can this be done in Photoshop by batch processing in some way?

Bill_de Loc: US

Google found this video for you.

http://helpx.adobe.com/photoshop/using/processing-batch-files.html

--

Kenny Loc: Oregon

Thanks, Bill de. This will accomplish my mission.

CaptainC Loc: Colorado, south of Denver

Just out of curiosity, why to you just want to change a bunch of images to 72PPI?

TheDman Loc: USA

No good reason, I'm sure. :)

rmalarz Loc: Tempe, Arizona

If I were to bet on it, it'd probably be for the same reason I do. My images for printing are 300dpi, per my printer's requirement. I reduce them to 72dpi for posting, emailing, etc.
--Bob

ronichas Loc: Long Island

I use/make actions to batch process all my photos, some for printing, some for the web. It just makes it easier whenever I am processing photos.

gvarner Loc: Central Oregon Coast

Keep in mind, dpi is printer resolution- dots per inch, - ppi is computer resolution - pixels per inch. Dpi for printing photos, ppi for viewing photos. It's a technicality for sure but leads to confusion at times in discussion forums.

amfoto1 Loc: San Jose, Calif. USA

You know, just "changing" an image from 300 ppi to 72 ppi doesn't actually change the size of the file in any way.

If an image is an 8x10" at 300 ppi, it's a 2400 x 3000 pixel image.

Convert it to 72 ppi and it's still 2400 x 3000 pixel, but now will show that it's 33.333 x 41.666 inches.

So you really haven't changed anything.

And, yes... ppi is a digital resolution while ppi is printer. Or, another way of looking at it is that ppi is digital while dpi is analog.

Many inkjet printers use several dots to print each pixel... so a printer might be 740 dpi or 1440 dpi, although digital files being used to make prints with it only need to be 240 ppi to be very high quality.

72 dpi is very low resolution... lower than even many newspapers use. Most magazines use at least 120 dpi and some as high as 140 or 170.

If the intent is to make smaller images for online display, I'd recommend using 100 ppi instead, since many (most?) modern monitors display at 96 ppi or higher. (72 ppi was the standard 10 or more years ago.)

If wanting to make smaller size files for online display, you need to change both the ppi and dimensions. In Lightroom, for example, you can tell it to export files at 100 ppi and no more than 600 or 700 pixels on the long side. You also can specify the size in ppi and inches, if preferred. If all the images are cropped to exactly the same aspect ratio you could even specify both dimensions.

For batch processing such as this, Lightroom is a much better bet than Photoshop. I honestly have never tried it and don't know how it would be done in Photoshop... I use LR for any such work. I only use PS for individual image editing and optimization.

Or, if you just want to resize a lot of images, a free program called FastStone Photo Resizer works quickly and well. I used it (before Lightroom existed) and it gives options similar to Lightroom. You simply select the images, then tell it to convert, and it goes to work making whatever changes you've set. It also can be used to do a lot of other things (such as adding a watermark, adding a border and more).

TheDman Loc: USA

This is like watching people argue over whether or not 2+2 equals 5, 6, or 8. You're all wrong! Nobody here has chimed in with anything correct (except ronichas, who wasn't talking about ppi). Click this link and read the whole article to see what I mean:

http://www.photoshopessentials.com/essentials/the-72-ppi-web-resolution-myth/

CaptainC Loc: Colorado, south of Denver

Come on amphoto you know better. For online display, the PPI figure is 100% irrelevant. 2000x3000 pixels will look the same at ANY ppi number - 72, 172, 372, or 732.

You had such a great answer going until you said that. NO modern monitor displays at 72. I think the Mac 5K displays are around 280. But of course, that too, is irrelevant.

The ONLY thing one needs to change is the pixel dimension. PPI is meaningless.

TheDman Loc: USA

There is no 'computer resolution'. Both dpi and ppi are related to printing. dpi is a property of your printer that tells you how many droplets of ink your printer's nozzles spray into every square inch of paper space. ppi instructs the printer to cram that number of your image's pixels into an inch of paper space. For viewing photos on a monitor, neither dpi nor ppi matter at all. Not one bit.

lamiaceae Loc: San Luis Obispo County, CA

I was wondering the same thing? Web?

Personally I work and archive in 300ppi and then to 150ppi for Web Publishing.

CaptainC Loc: Colorado, south of Denver

PPI is irrelevant for the web. ONLY pixel dimension.

lamiaceae Loc: San Luis Obispo County, CA

Not this again, ppi - dpi, if Adobe can't keep it straight do we really care. Most of us know what we mean in the context that we (mis-) use either term.