Photoshop: Measure tool for curved objects

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  • Updated 9 months ago
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I'd like to recommend the measurement tool in the extended version of photoshop be updated in a future release to include the ability to measure curved objects.
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Doug Ware

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Posted 5 years ago

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Chris Cox

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How do you need to measure them? What kinds of curved objects?
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Doug Ware

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The request is for applications using microscope images, however, I'm sure there would be similar needs outside microscopy. I'm able to set a customized measurement scale that was a great feature introduced in cs3 but photoshop limits measurement to straight lines. The alternate method I use is a cumbersome cumulative addition of multiple straight line measurements.
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Chris Cox

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Again: WHAT are you trying to measure about the curved objects? There are thousands of possible things that could be measured, and we need to know what one(s) you are interested in.
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Jeffrey Tranberry, Sr. Product Manager, Digital Imaging

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Are you trying to measure the area? The circumference?
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Doug Ware

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My need is generally in determining length of fibers that are typically curved. I've also have needs of determining area as well as perimeters but these I can get by various use of the lasso or wand tools tools in capturing the subject in question. Curved measures I only know how to determine by addition of multiple line progressions.
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Chris Cox

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Ok, so centerline measurements.
And good to know that you need area and perimeter as well.

Manually dragging out curves usually leads to problems in precision.
But we'll have to see what we can come up with.

And we'll have to examine the other analysis features to see if they can do a bit more with automated methods.
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Doug Ware

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That would be great. Thanks for taking time on the request!
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David Jensen

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In a couple of my scripts, I have a function that calculates the length of a path. Would this be useful to you?

Or are you looking for a more automatic method, where you wouldn't even need to manually make a path?
I just thought of a method for getting a centerline that seems to work fairly well.
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Colin Heaney

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hello david I would love to have a way to measure the length of a path if you can help. I am not sure how these forums work but my email is colin@colinheaney.com
thank you
Colin
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Charlotte Capistran

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I know these posts are old, but a way to measure the length of a curved path would be really useful for me! If you have a scripts that gives you this function, it would be amazing for me to have access to it :)
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John Browning

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I think you'll find my method works. I use it to measure the length of curved lines.
A variant is to have a separate Layer,  stroke your path  in this Layer but instead of using the magic wand to select the stroke line, just use the "selected layer" option in Histogram window. Let me know how you get on.
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Eric Neilsen

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I would be great to measure river miles too. Using a straight line tool just doesn't get you close enough. Trace the river and there you have it. But the same could be said of a hair, or small curly object.
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John Browning

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I have found a (rather long-winded but accurate) way to measure the length of a curve.
1.Construct a path to follow the curve
2.Stroke the path with a line (call it A) of known pixel width
3. Using the same pixel width, draw a straight line of known length (Call it B)
4. Select line A (use magic wand with tolerance set to get all of the line)
5. Open Histogram window and use the rotating arrows symbol (uncached refresh) to bring cache level to 1
6. Note down the number of pixels.Call PA
7. Select known line B and do the same to get the number of pixels. Call PB
8. Because the lines are the same number of pixels wide, the ratio of PA to PB is the ratio of the line lengths. Since we know the length of line B, we can work out the length of line A.
9, To check the method, draw a circle (as line A). the length of this line is, of course, the circumference. By using the straight measuring tool, you can measure the diameter and hence, work out the circumference. Draw your straight line of known length and use the method described.
 The two numbers (Pi X diameter  and the result of the ratio method) should agree.