How to measure images?

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jonnylim

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Jonny
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Can anyone know how can I measure the image sizes in centimeters or inches?

I mean is there any program that I can use to measure images?

I'd like to appreciate your recommendation.

Thanks
 
Images are measured in pixels on a computer. Generally when printing you print at 300dpi, which is dots per inch, with each pixel being a dot. so a 3000px wide image would print 10" wide.

The dpi changes depending on how close you intend to view the image when printed.
 
Hi Jonny and welcome to TP

I think you need to explain more about what you are trying to do/achieve?

For example, I surmise that you are wanting to measure screen displayed image? Though to what end, how will knowing the size on cm or inches help you.
 
Hi @Box Brownie

Actually, I am looking for something that can make it easy to measure images on the monitor screen.

Let me know if you need more clarification.
 
jonnylim said:
Hi @Box Brownie

Actually, I am looking for something that can make it easy to measure images on the monitor screen.

Let me know if you need more clarification.
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In the past I have simply used a ruler held against the screen.

I never had a need to find a program to measure 'on screen'.
 
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I think you need to be careful as measuring an image on a monitor is one thing but if printed it possibly wont be the same size.

So I think it depends what you want to do and why.

Why do you want to measure an image on a screen?
 
jonnylim said:
Hi @Box Brownie

Actually, I am looking for something that can make it easy to measure images on the monitor screen.

Let me know if you need more clarification.
Click to expand...
As I asked, if you explained reason for the requirement it is likely you will get more informed advice.

FWIW I don't ever recall your question arising on any of the various photography forums I member of!
woof woof said:
I think you need to be careful as measuring an image on a monitor is one thing but if printed it possibly wont be the same size.

So I think it depends what you want to do and why.

Why do you want to measure an image on a screen?
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Exactly!
 
Box Brownie said:
FWIW I don't ever recall your question arising on any of the various photography forums I member of!
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On the surface of it, there is no answer.
On the screen it will depend on how you zoom it, and on print it will depend on what size you set it to print.
Pixel numbers would be more useful if you want to work out what the maximum print/display size would be at a resolution acceptable for its purpose
 
Yes, it's nearly like a ruler. But not a physical one. I need something that is easier than physically putting a ruler against the monitor. So, I can adjust the images on the screen and assure that it's 6 inches long.
 
jonnylim said:
Yes, it's nearly like a ruler. But not a physical one. I need something that is easier than physically putting a ruler against the monitor. So, I can adjust the images on the screen and assure that it's 6 inches long.
Click to expand...
But that won't be the same on other monitors of a different size or resolution to yours

If it is just on yours, work it out from the resolution of your monitor to see how many pixels wide you need it to display that size, then set your image width to that number of pixels
 
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jonnylim said:
Yes, it's nearly like a ruler. But not a physical one. I need something that is easier than physically putting a ruler against the monitor. So, I can adjust the images on the screen and assure that it's 6 inches long.
Click to expand...

Jonny, I think you really need to think about why you're doing this and to what end / application.
 
Well, I know that it's odd for you all. But I personally have a few different use cases where I am currently putting the physical ruler on a monitor. For example, I sometimes want an image that is an exact dimension on the screen or to measure things on the screen to calculate proportions from online images.

I'm sorry I can see that it's becoming more complicated than I expected. There are so many online ruler applications available(i.e: https://ruler-online.net) and I have tried some of them. They are making my work a bit simple because I don't need to place the physical ruler. But it is still complex to measure images on these online ruler applications. I need something that can help me to do the measurements more simple and quick way.
 
I just can't see how this works as how big the image is on screen is often IMO pretty much meaningless.

I hope you find what you're looking for but I worry that you're on completely the wrong track here.

Good luck with it.
 
jonnylim said:
Well, I know that it's odd for you all. But I personally have a few different use cases where I am currently putting the physical ruler on a monitor. For example, I sometimes want an image that is an exact dimension on the screen or to measure things on the screen to calculate proportions from online images.

I'm sorry I can see that it's becoming more complicated than I expected. There are so many online ruler applications available(i.e: https://ruler-online.net) and I have tried some of them. They are making my work a bit simple because I don't need to place the physical ruler. But it is still complex to measure images on these online ruler applications. I need something that can help me to do the measurements more simple and quick way.
Click to expand...
You clearly(?) have a very specific (to you) requirement but unless you feel able to state the specifics of exactly what you are doing no one can guide you through your dilemma.

One surmise I could make is that a CAD/CAM type of program might do what you are talking about.........but I have no idea if such programs can 'read' the likes of a jpeg, gif, PNG or similar image files?

I hope you can find a solution that suits you.
 
Photoshop has a measure function and will tell you the number of pixels between two points. How that corrolates into real life depends on other factors including screen resolution and the DPI/PPI setting of the image in question.

I've used this function to assist with working out geometry. Eg with a photograph of a side on view of the car, the car I can corrolate the published wheelbase measurement against the number of pixels, and from that can work out the lengths or heights of other components on the same plane as the the original measurement took place. Items in front or behind that reference plane will measure slightly differently.
 
Doing what I suggested above, an image 845 pixels wide is exactly 6" on my screen.

If I want to measure parts of an image (last week I needed to make a part for a rotovator and only had a picture of it, but from the specs I knew the diameter of the tines) I import it into CorelDraw then make a ruler using a known dimension, then use that ruler to measure other parts on the image.
You can set up the dimensioning tool to do it automatically between points.
But it has little to do with the displayed size on the screen, that depends on the zoom level.

But realistically, as others have said, with such a vague idea of what you are doing, you are not likely to get the solution you want.
 
If you paste an image into something like MS Word, you can set the dimensions in inches/centimetres and work from there. Obviously, youll need to set the paper size to match your monitor.
 
Anyone who really wants to get a feel for how confused and confusing the whole issue is, should read this Wikipedia article: https://en.wikipedia.org/wiki/Pixel

Bottom line: first define your... :naughty:

Pixel.JPG
 
sk66 said:
You have to have a known first... either a known object size/dimension of something in the image (comparing relative sizes in an image ), or the pixel pitch your display is set to (setting physical size on your display).

View: https://youtu.be/xXE7MBiWJIc
Click to expand...
Thank you guys for your wonderful support.

I got my answer from this video. It exactly does what I want.

But @sk66 can I change the measurement unit from pixels to inches in this software?
 
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Digital images do not have physical sizes until printed or displayed. Change the display & you change the size...
If you are printing the images your printer driver should give you the option of specifying the size. If the image is very low resolution it may look awful printed to a moderate size, but old 6MP images print just fine to A4 even when viewed close up.
Photoshop & many other similar packages allow the datafile to be enlarged & extra data extrapolated to fill the gaps. This would allow a 6MP image to be printed to fill a wall. Detail would be lacking but it will look OK from a distance.

Some software allows the pixels per inch to be changed (72 & 300 are the old standard values) but hardly anything pays an attention to the values assigned.
 
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