Crop Photos Pixel Calcalutions

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

  1. thankyou

    thankyou Guest

    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
    #1
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  2. thankyou

    thankyou Guest

    I must add....

    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
    #2
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  3. thankyou

    John Navas Guest

    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.



    Here's a Google Spreadsheet to calculate what you want:
    http://spreadsheets.google.com/ccc?key=rDMiC6CxltvMg2HZDaC0NBA

    (Save it for yourself before I delete it.)

    --
    Best regards,
    John (Panasonic DMC-FZ28, and several others)
    John Navas, Jun 19, 2009
    #3
  4. thankyou

    ray Guest

    On Thu, 18 Jun 2009 18:27:57 -0700, 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?
    >
    > 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
    #4
  5. thankyou

    thankyou Guest

    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
    #5
  6. thankyou

    thankyou Guest

    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
    #6
  7. thankyou

    John Navas Guest

    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
    #7
  8. 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
    #8
  9. thankyou

    thankyou Guest

    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
    #9
  10. thankyou

    John Navas Guest

    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
    #10
  11. thankyou

    Bob Williams Guest

    thankyou wrote:
    > I must add....
    >
    > 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
    #11
  12. thankyou

    thankyou Guest

    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
    #12
  13. thankyou

    Bob Larter Guest

    Bob Williams wrote:
    > thankyou wrote:
    >> I must add....
    >>
    >> 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
    #13
  14. thankyou

    John Navas Guest

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

    >thankyou wrote:
    >> I must add....
    >>
    >> 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
    #14
  15. thankyou

    John Navas Guest

    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
    #15
  16. thankyou

    thankyou Guest

    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
    #16
  17. thankyou

    thankyou Guest

    thankyou, Jun 19, 2009
    #17
  18. thankyou

    ray Guest

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

    > 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


    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
    #18
  19. thankyou

    ray Guest

    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
    #19
  20. thankyou

    Bob Williams Guest

    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
    #20
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