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Author Topic: Resizing the Image in PS Based on Desired Size in Megapixels  (Read 1618 times)

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« on: November 16, 2016, 16:42 »
0
Guys, can someone tell me if there is a way to resize an image in Photoshop to a certain number of Megapixels? What I mean is, when I open the Image Resize box, I can change the dimensions of the image, however, if for example I want my final image to be close to 6 MPix, I have to use the calculator every time I change any of the image dimensions, and manually calculate the final size by multiplying the number of pixels of the width and height. Is there a way to see what is the final size in megapixels while changing the dimensions?


« Reply #1 on: November 16, 2016, 17:01 »
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I don't think so. You can always get a rough idea by just multiplying the left-most digit in the width and height. If your image is a wonky size, that will only get you close, but if it's 6,000 x 4,000, you'll know it's 24 megapixels.

« Reply #2 on: November 16, 2016, 17:05 »
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Yeah, I thought so... That's what I do. I just thought somebody from Adobe already thought some people might need this feature, but it was hidden somewhere lol.

Thanks!

ShadySue

« Reply #3 on: November 16, 2016, 17:10 »
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Presumably you're talking about uncompressed size?
Jpeg size depends as much on the file itself as the dimensions, even if saved at '12' quality.

« Reply #4 on: November 16, 2016, 17:13 »
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The "pixels dimension" readout in the resize dialogue box for an 8-bit jpg image is 3x the number of pixels as near as makes no difference, so it's quite easy to fiddle with the height or width number and read off how many megapixels you have from "pixel dimensions".
I don't know anywhere where you can enter your desired number directly.

« Reply #5 on: November 16, 2016, 17:14 »
+1
Presumably you're talking about uncompressed size?
Jpeg size depends as much on the file itself as the dimensions, even if saved at '12' quality.
That's the amount of memory the saved file uses, Sue, not the MP size.

ShadySue

« Reply #6 on: November 16, 2016, 17:22 »
+1
Presumably you're talking about uncompressed size?
Jpeg size depends as much on the file itself as the dimensions, even if saved at '12' quality.
That's the amount of memory the saved file uses, Sue, not the MP size.
Sorry, you are totally right.

« Reply #7 on: November 16, 2016, 17:55 »
0
Presumably you're talking about uncompressed size?
Jpeg size depends as much on the file itself as the dimensions, even if saved at '12' quality.
That's the amount of memory the saved file uses, Sue, not the MP size.
Yeah, I know about the pixel size, but that's not really precise. Also, if I use pixel size as a reference, I still have to divide it in my head or on the calculator by 3 to get only the rough number of megapixels. Funny that there is no number in the image resize box that would show the exact number in megapixels whenever you change the dimensions.

« Reply #8 on: November 17, 2016, 02:19 »
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In Lightroom you can export the image to an arbitrary megapixel size.

« Reply #9 on: November 17, 2016, 12:20 »
+2
You have tweaked my curiosity here, so I tried modifying a couple of scripts (originally from istock contributor theasis and Sean Locke) in an attempt to do it...  you can get it from here:

MP Resize

Either right click and "Save link as..." or left click and copy and paste to a text file, then save as a ".jsx".

Put it in the Photoshop program directory under "Presets\Scripts" and it should become visible on the File/Scripts menu.

When run, it will display the size of the active image width and height in pixels, along with an approximate megapixel size (width x height).  You can enter a new megapixel size and it will display the approximate dimensions that would result, then when you're happy you can tell it to go ahead and resize the image if you want.  The result may not be exactly the size predicted (rounding errors I presume) but it should be close.

Caveat: I'm not a JavaScript programmer so I don't vouch for either the quality or the functionality.  It seems to work but use at your own risk!


« Reply #10 on: November 17, 2016, 14:48 »
+1
In Lightroom you can export the image to an arbitrary megapixel size.

esp'ly useful; since you can run it on batches & automatically rename files


 

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