# Crop Photos Pixel Calcalutions

Discussion in 'Digital Photography' started by thankyou, Jun 19, 2009.

1. ### thankyouGuest

I’ve posted on this subject last week. Enlarge Digital Photos.

Is there a trick to this cropping and/or aspect changing thing?

Mostly cropping to fit a desired aspect ratio?

My Canon 350D is 3:2 @ 3465x2304 pixels, that’s a 1.5 ratio, perfect
for at 18x12 or 6x4 print.

Ok, got that, thanks for your help.

But, If I want to print a 5x7 at 1.4 ratio how do I figure out the
number of pixels to crop on one and/or each of the sides of my
3465x2304 pixel, 1.5 ratio?

Or if I want to print a 10x8 at 1.25 ratio how do I figure out the
number of pixels to crop on one and/or each of the side?

Can someone help me with the math formula? The variations are endless,
so is there some trick or suggestions?

I'd like to do this in Canon DPP or IrvanView.

Regards, John

thankyou, Jun 19, 2009

2. ### thankyouGuest

I have a copy of PS 6 or 7 that is mothballed and/or if there is a
program I should buy that makes this process simple, please, give me a
suggestion.

thankyou, Jun 19, 2009

3. ### John NavasGuest

On Thu, 18 Jun 2009 18:27:57 -0700 (PDT), thankyou <>
wrote in
<>:

>I’ve posted on this subject last week. Enlarge Digital Photos.
>
>Is there a trick to this cropping and/or aspect changing thing?
>
>Mostly cropping to fit a desired aspect ratio?
>
>My Canon 350D is 3:2 @ 3465x2304 pixels, that’s a 1.5 ratio, perfect
>for at 18x12 or 6x4 print.
>
>Ok, got that, thanks for your help.
>
>But, If I want to print a 5x7 at 1.4 ratio how do I figure out the
>number of pixels to crop on one and/or each of the sides of my
>3465x2304 pixel, 1.5 ratio?
>
>Or if I want to print a 10x8 at 1.25 ratio how do I figure out the
>number of pixels to crop on one and/or each of the side?
>
>Can someone help me with the math formula? The variations are endless,
>so is there some trick or suggestions?
>
>I'd like to do this in Canon DPP or IrvanView.

(Save it for yourself before I delete it.)

--
Best regards,
John (Panasonic DMC-FZ28, and several others)

John Navas, Jun 19, 2009
4. ### rayGuest

On Thu, 18 Jun 2009 18:27:57 -0700, thankyou wrote:

> Iâ€™ve posted on this subject last week. Enlarge Digital Photos.
>
> Is there a trick to this cropping and/or aspect changing thing?
>
> Mostly cropping to fit a desired aspect ratio?
>
> My Canon 350D is 3:2 @ 3465x2304 pixels, thatâ€™s a 1.5 ratio, perfect for
> at 18x12 or 6x4 print.
>
> Ok, got that, thanks for your help.
>
> But, If I want to print a 5x7 at 1.4 ratio how do I figure out the
> number of pixels to crop on one and/or each of the sides of my 3465x2304
> pixel, 1.5 ratio?
>
> Or if I want to print a 10x8 at 1.25 ratio how do I figure out the
> number of pixels to crop on one and/or each of the side?
>
> Can someone help me with the math formula? The variations are endless,
> so is there some trick or suggestions?
>
> I'd like to do this in Canon DPP or IrvanView.
>
> Regards, John

Basically, to change from 'what you have' to 'what you want', you divide
the width by 'what you have' and then multiply by 'what you want'. Here's
an example:

you have 3465x2304 which is 1.5 aspect ratio and you want 1.4 aspect
ratio. 3465/1.5 * 1.4 = 3234. So you want to crop so you have dimensions
of 3234x2304. So you need to remove 3465 - 3234 = 231 pixels from the
width - 231 from one side or 115 from one side and 116 from the other
side.

ray, Jun 19, 2009
5. ### thankyouGuest

Thanks Ray.

That’s a good formula. Yep, 3234/2304 = 1.4

Question:

Playing around. When when I divide the height 2304 (instead of the
width) by 1.5 and then multiply by 1.4, I get 1.6 aspect ratio.
2304/1.5*1.4 = 2150
3465/2150 = 1.6

Ok, makes sense, we're increasing the difference, but, (This is
stupid, right?) why doesn't it work and could there be a formula to
figure it out that way?

Really good and useful answer BTW. This one will get some use.

Thank you very much.

J

thankyou, Jun 19, 2009
6. ### thankyouGuest

Actually, can I take my question BACK.

I'd much rather know, which program can do this easily? Am I supposed
to grab a corner of the photo in IrvanView and work from there? Can I
do this in Canon DPP?

I'm thinknig the best would be a program where I can fill in a H x W
box with the numbers to adjust the pixels.

John

thankyou, Jun 19, 2009
7. ### John NavasGuest

On Thu, 18 Jun 2009 21:05:58 -0700 (PDT), thankyou <>
wrote in
<>:

>Actually, can I take my question BACK.
>
>I'd much rather know, which program can do this easily? Am I supposed
>to grab a corner of the photo in IrvanView and work from there? Can I
>do this in Canon DPP?
>
>I'm thinknig the best would be a program where I can fill in a H x W
>box with the numbers to adjust the pixels.

Photoshop Elements (recommended) will do this for you automatically.

--
Best regards,
John (Panasonic DMC-FZ28, and several others)

John Navas, Jun 19, 2009
8. ### Jürgen ExnerGuest

thankyou <> wrote:
>I’ve posted on this subject last week. Enlarge Digital Photos.
>
>Is there a trick to this cropping and/or aspect changing thing?
>
>Mostly cropping to fit a desired aspect ratio?
>
>My Canon 350D is 3:2 @ 3465x2304 pixels, that’s a 1.5 ratio, perfect
>for at 18x12 or 6x4 print.
>
>Ok, got that, thanks for your help.
>
>But, If I want to print a 5x7 at 1.4 ratio how do I figure out the
>number of pixels to crop on one and/or each of the sides of my
>3465x2304 pixel, 1.5 ratio?
>
>Or if I want to print a 10x8 at 1.25 ratio how do I figure out the
>number of pixels to crop on one and/or each of the side?

Doesn't matter. Pick any two numbers as long as one number divided by
the other number is 1.4 resp. 1.25.

jue

Jürgen Exner, Jun 19, 2009
9. ### thankyouGuest

Thanks John.

In Photoshop Elements, will I be able to choose which side of the
photo to crop off to get the aspect ratio I'm looking for?
Just saying, 'cause "automatically" sounds like the crap I'm getting
from the commercial photo shops.

-------

Jurgen, I think I answer my own "take back" question.

To change the aspect ratio from 1.5 to 1.4 you have to decrease the
difference between Lenght/Width. You can do that by reducing the
length or increasng the width. Ray taught us how to decrease the
Length. If we were able to increase the width to 2470, then we'd have
3465/2470 - = 1.4.

But, of course we can't "really" do that.

thankyou, Jun 19, 2009
10. ### John NavasGuest

On Thu, 18 Jun 2009 21:49:53 -0700 (PDT), thankyou <>
wrote in
<>:

>Thanks John.
>
>In Photoshop Elements, will I be able to choose which side of the
>photo to crop off to get the aspect ratio I'm looking for?
>Just saying, 'cause "automatically" sounds like the crap I'm getting
>from the commercial photo shops.

In Photoshop Elements, click the Crop tool, specify print dimensions,
then use the tool to select the area you want to print, and it will
match the aspect ratio of the print.

Easier to do than to write -- works very well, dead simple. And
Photoshop Elements is superb for other things as well.

--
Best regards,
John (Panasonic DMC-FZ28, and several others)

John Navas, Jun 19, 2009
11. ### Bob WilliamsGuest

thankyou wrote:
>
> I have a copy of PS 6 or 7 that is mothballed and/or if there is a
> program I should buy that makes this process simple, please, give me a
> suggestion.

With either PS 6 or 7 it is an absolute piece of cake.
1) Select the Crop Tool.
2) Type into the height and width box, whatever size you want the image
to be e.g., 4"x6", 5x7, 8x10, 11x14, 7.02x10.53......whatever.
The crop tool will yield an image of exactly those dimensions.
As an added bonus, if you type in 300ppi in the resolution box, the
image will not only be cropped to the right height and width but will
contain enough pixels to create an excellent quality print.
Bob Williams

Bob Williams, Jun 19, 2009
12. ### thankyouGuest

Bob, thanks for the above.

In PS 6/7, what happens to the photo (pixels) when one chooses a print
size (i.e. 4x7, 5x7….)
Is there any control over which pixels are lost?

You wrote: "The crop tool will yield an image of exactly those
dimensions."

In the Ray’s example above, we have to “lose” 231 pixels in length for
a 3:2 (1.5) to become a 5x7 (1.4).
As you say, typing in the HxW is super easy, but, having control over
the lost pixels could be important for the photo composition.

John
If Photoshop Elements has control, 100% PS can do it better.

thankyou, Jun 19, 2009
13. ### Bob LarterGuest

Bob Williams wrote:
> thankyou wrote:
>>
>> I have a copy of PS 6 or 7 that is mothballed and/or if there is a
>> program I should buy that makes this process simple, please, give me a
>> suggestion.

>
> With either PS 6 or 7 it is an absolute piece of cake.
> 1) Select the Crop Tool.
> 2) Type into the height and width box, whatever size you want the image
> to be e.g., 4"x6", 5x7, 8x10, 11x14, 7.02x10.53......whatever.
> The crop tool will yield an image of exactly those dimensions.
> As an added bonus, if you type in 300ppi in the resolution box, the
> image will not only be cropped to the right height and width but will
> contain enough pixels to create an excellent quality print.

200ppi will work fine too.

--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------

Bob Larter, Jun 19, 2009
14. ### John NavasGuest

On Fri, 19 Jun 2009 00:55:46 -0700, Bob Williams <>
wrote in <7wH_l.2258\$>:

>thankyou wrote:
>>
>> I have a copy of PS 6 or 7 that is mothballed and/or if there is a
>> program I should buy that makes this process simple, please, give me a
>> suggestion.

>
>With either PS 6 or 7 it is an absolute piece of cake.
>1) Select the Crop Tool.
>2) Type into the height and width box, whatever size you want the image
>to be e.g., 4"x6", 5x7, 8x10, 11x14, 7.02x10.53......whatever.
>The crop tool will yield an image of exactly those dimensions.

Yep.

>As an added bonus, if you type in 300ppi in the resolution box, the
>image will not only be cropped to the right height and width but will
>contain enough pixels to create an excellent quality print.

Unless you know what you are doing with a specialized tool like Genuine
Fractals, any necessary up- or down-sampling is best left to the printer
driver.

--
Best regards,
John (Panasonic DMC-FZ28, and several others)

John Navas, Jun 19, 2009
15. ### John NavasGuest

On Fri, 19 Jun 2009 07:05:56 -0700 (PDT), thankyou <>
wrote in
<>:

>Bob, thanks for the above.
>
>In PS 6/7, what happens to the photo (pixels) when one chooses a print
>size (i.e. 4x7, 5x7….)
>Is there any control over which pixels are lost?

Yes -- you draw the crop over the image whatever way you want.

>If Photoshop Elements has control, 100% PS can do it better.

Not necessarily. PSE is simply the best bits from PS.

--
Best regards,
John (Panasonic DMC-FZ28, and several others)

John Navas, Jun 19, 2009
16. ### thankyouGuest

Ok, got it, some really good stuff here, thanks all of you.

NOW:
If I could only find 12" X 18" FRAMES that sell for around the same
price as \$11.99 for TWO (16" x 20") at Target.

John

thankyou, Jun 19, 2009
17. ### thankyouGuest

thankyou, Jun 19, 2009
18. ### rayGuest

On Thu, 18 Jun 2009 20:56:52 -0700, thankyou wrote:

> Thanks Ray.
>
> Thatâ€™s a good formula. Yep, 3234/2304 = 1.4
>
> Question:
>
> Playing around. When when I divide the height 2304 (instead of the
> width) by 1.5 and then multiply by 1.4, I get 1.6 aspect ratio.
> 2304/1.5*1.4 = 2150
> 3465/2150 = 1.6
>
> Ok, makes sense, we're increasing the difference, but, (This is stupid,
> right?) why doesn't it work and could there be a formula to figure it
> out that way?
>
>
> Really good and useful answer BTW. This one will get some use.
>
> Thank you very much.
>
> J

If you decrease the maximum dimension, you decrease the aspect ratio. If
you decrease the minimum dimension, you increase the aspect ratio.

ray, Jun 19, 2009
19. ### rayGuest

On Thu, 18 Jun 2009 21:05:58 -0700, thankyou wrote:

> Actually, can I take my question BACK.
>
> I'd much rather know, which program can do this easily? Am I supposed to
> grab a corner of the photo in IrvanView and work from there? Can I do
> this in Canon DPP?
>
> I'm thinknig the best would be a program where I can fill in a H x W box
> with the numbers to adjust the pixels.
>
> John

As I recall, it's quite easy in GIMP. That's not something I do routinely.

ray, Jun 19, 2009
20. ### Bob WilliamsGuest

thankyou wrote:
> Ok, got it, some really good stuff here, thanks all of you.
>
> NOW:
> If I could only find 12" X 18" FRAMES that sell for around the same
> price as \$11.99 for TWO (16" x 20") at Target.
>
> John
>

Buy the 16 x20 frames and mat your picture to fit the frame.
It will look more professional to boot.
OR
Crop the image to 16x20, send it out for printing and then mount it in
the 16x20 frames...............Voila!......Done.
Bob Williams

Bob Williams, Jun 19, 2009