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Photoshop - Cut image into equal parts

#1 User is offline   FallenApple 

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Posted 14 May 2004 - 01:34 PM

Can anyone lend me some Photoshop advice on cutting an image into three equal parts? The aim of this is so I can print each to its own sheet of paper and then glue them together for a project I am working on. The slice guide is close but not quite equal.
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#2 User is offline   Philbert 

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Posted 15 May 2004 - 10:47 AM

The only way I know to do this is kind of convoluted but it does work.
Make a new layer and using the line tool, draw a short, 1 pixel line anywhere in the image. (Use shift to keep the line straight and drag horizontally or vertically - depending on which direction to you want to split)
Duplicate the layer 3 times for a total of 4.
Take one of the lines and drag to the edge of the image. (it should snap to the edge)
In another layer, drag a line to the opposite side.
Link all 4 layers.
Now hit the Distribute layers button in the align layers pallet (again, horiz or vert, depending..), and the two lines in the middle will jump to the points where you have three perfectly equal sections.
You could crop to those lines by eye-balling, but it would be better to drag ruler guides so they cover the lines. That way, when you crop for each of the three images, the crop tool will snap to the guides.
HTH ...
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#3 User is offline   FallenApple 

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Posted 15 May 2004 - 11:46 AM

Thanks Phil, I'll give that a try. Sounds like exactly what I need.
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#4 User is offline   ado_thetechy 

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Posted 16 May 2004 - 03:22 AM

What you need to do is check the length of your document - you can do it on the ruler or by going image > image size and divide it by three. Then to break it up go view > New Guide and insert the length of the division. Then check snap-to guides is on. When you do that you can use the crop tool to crop each part. Crop, save, undo.
Hope this helps.
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#5 User is offline   Philbert 

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Posted 16 May 2004 - 06:02 AM

You mean use MATH! /forums/ubbthreads/images/graemlins/shocked.gif
eewwww ....
No, that would certainly work but you've sparked another idea that would be even easier.
Select New Guides from the view menu but instead of using the ruler and division to figure out where the guides would go, just use percentage! Photoshop is smart enough to know what a "%" means in the New Guides dialog box.
In Fallen's case, place the first guide at 33.33 % and the second at 66.66 %. Boom - three perfectly equal sections!
Thanks for putting my brain into gear. /forums/ubbthreads/images/graemlins/wink.gif
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#6 User is offline   dougster 

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Posted 17 May 2004 - 04:46 PM

Just adding to -phil's (brain) Guide idea. After you have the 3 divided properly take the rectangular marquee (M) and select the first part. Then (V) move tool, drag to a New File of the same DPI. Do this on the other two the same way. This worked well after scanning a large poster, and then cutting, and placing them together came out sweet.
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#7 User is offline   Philbert 

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Posted 17 May 2004 - 06:25 PM

Ahh ... good tip. That'd be much better/easier than using crop tool and back-tracking using the history pallet.
I'll go you one better tho' ... instead of using the move tool and dragging the marquee'd section to a new document (which would mean you'd have to pay attention to the selection size and image resolution beforehand), just Command+C (Copy), after you make the selection.
Now, simply make a new document and Photoshop will automatically default to "Clipboard" - which will be sized EXACTLY to the dimensions and resolution of the copied selection - no thinking required!
Ain't Photoshop cool! /forums/ubbthreads/images/graemlins/grin.gif
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#8 User is offline   dougster 

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Posted 18 May 2004 - 06:54 AM

-phil
In reply to:

- no thinking required!


...copy the sucker is a good one, and NO -- math da-boot /forums/ubbthreads/images/graemlins/grin.gif
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#9 User is offline   jleslie 

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Posted 18 May 2004 - 07:33 AM

You could also determine the size of the document when quartered (e.g., if it's 8-1/2" x 11," one quarter would be 4-1/4" x 5-1/2"). Then go to the <Image> pull-down menu and go to <Canvas Size>. Plug in the "quarter-size dimensions" and crop the canvas from each of the extreme four corners (in four separate operations, starting each time from the original). Make sure you save the original to start from each time (or revert to original state) and re-name each of the 4 quarters so you don't overwrite the original.
-Judy
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#10 User is offline   Billman 

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Posted 19 May 2004 - 07:40 AM

I use math for small images, like dicing them for online purposes. A suggestion if you need/want to do the math -- use pixels not inches! This eliminates the fudge factor created by the finite number of decimals Photoshop can calculate.
The cropping by Canvas size is great for halves or fourths, since it's a very effective way to avoid missed or overlapped pixels, but I like the Copy selection/New Document method for sixths or uneven divisions.
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