5 Replies Latest reply on May 8, 2014 4:48 AM by John Waller

# How can I get the actual dimensions of an item in a photo?

Hi -

I've been tasked to provide the actual measurements of items in photographs. (There are 300 different photos so I'm hoping a fairly direct solution can be found.)

My thought process was to open a photo, drag a bounding box around the item with the Marque Tool, and read the measurements in the Info panel.  But it's not working out too well.

For the sake of discussion, let's say that I have a photo of a simple, plastic, "happy meal" type badge/toy.  The badge is actually 1" square.

When I drag the box around it the Info panel tells me that it measures W:3.37" X H:3.37".

I can't figure out how to get W:1" x  H:1" to appear in the Info panel.

The photo's dimensions show a whopping 66" x 44" at 72ppi, and it looks like all 300 of these photos have the same dimensions so one solution should fit all.

So the question is - using Photoshop, how to I learn the actual, physical measurements of an item in a photo?

I thought this should be simple but it's turning out to be a real puzzle.

TIA any expert input.

Josh

• ###### 1. Re: How can I get the actual dimensions of an item in a photo?

You need to open the Image Size dialog box (Ctrl Alt i or Cmd Opt i on a Mac).  Make sure Resample is _not_ checked, and that the Width is set to Inches.  Now do some math:

In your case size of your selection is indicated as 3.37 inches, but you know the actual size is 1 inch, so you need to multiply whatever is in the Resolution field by 3.37

So if it is 72 the resolution needs to be 242.64

Make that change and OK it

Drag another sample around the badge to check the size is now right.

Remember: Resample needs to be unchecked in the Image Size dialog box.

• ###### 2. Re: How can I get the actual dimensions of an item in a photo?

See these articles about Photoshop and forensic measurements:

http://forensicphotoshop.blogspot.ca/2007/10/let-me-count-ways.html

http://www.fourandsix.com/blog/2011/9/26/photogrammetry-101.html

Be sure to open the Measurement Log palette under the Window menu as well.

BTW, does anyone know if there is a quick way to set the measurement scale of the ruler tool? In Photoline I can take a measurement of any width or height, and it will ask me what the actual physical size of the object in the image is (just hold down the <ctrl> key while dragging the ruler tool, and a popup dialog comes up). Is there a quick and dirty method in Photoshop too?

• ###### 3. Re: How can I get the actual dimensions of an item in a photo?

Trevor - Thanks for the quick response. That worked fine.

• ###### 4. Re: How can I get the actual dimensions of an item in a photo?

Herbert2001 - Thanks for the response.  I'll get to those articles soon but Trevor's formula works great.

BTW  - I don't have a Measurement Log palette under Window or elsewhere.

• ###### 5. Re: How can I get the actual dimensions of an item in a photo?

BTW  - I don't have a Measurement Log palette under Window or elsewhere.

That's found in Photoshop CC or any Extended version of Photoshop