Specific-Size Crop

StevenVStevenV Registered Users Posts: 1,174 Major grins
edited February 11, 2006 in Finishing School
Is there a way to get a specific-size crop from PhotoShop?

I can use the Crop tool, but from what I understand that does interpolation - so it throws bits away or creates new ones based on the amount of data I've selected and the size I tell it I want it to be. If I say I want 800px by 600px but select a smaller section of an image than that, it creates some new data.

And hey, if the above paragraph is incorrect please point me to a more accurate description.

What I want is to be able to use the marquee tool - but have it draw only a box of size that I've specified - and then use the Image->Crop command.

Is it possible?
Am I insane?


Arrrr. icon_pirate.gif
-Steven
my words, my "pro"pictures, my "fun" pictures, my videos.

Comments

  • DavidTODavidTO Registered Users, Retired Mod Posts: 19,160 Major grins
    edited January 27, 2006
    yeah, use marquee, set it to a specific pixel size. I then copy, make new, paste.
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  • AndyAndy Registered Users Posts: 50,016 Major grins
    edited January 27, 2006
    I'm sure David meant to be more thorough:
    Andy

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  • DavidTODavidTO Registered Users, Retired Mod Posts: 19,160 Major grins
    edited January 27, 2006
    Andy wrote:
    I'm sure David meant to be more thorough:


    No, actually I meant to be obtuse and obfuscate.
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  • StevenVStevenV Registered Users Posts: 1,174 Major grins
    edited January 27, 2006
    DavidTO wrote:
    No, actually I meant to be obtuse and obfuscate.

    that's what I was hoping for :):

    Thanks guys. I've got to start poking around those settings bars more - I had never changed the crop's "style" from "normal" or even really noticed that it was settable... even when I was trying to figure out the answer myself.
    -Steven
    my words, my "pro"pictures, my "fun" pictures, my videos.

  • RhuarcRhuarc Registered Users Posts: 1,464 Major grins
    edited January 27, 2006
    Does teh crop tool in photoshop really cause it to interpolate data? I was under the impression that all the crop tool did was change the size, not anything else about the picture. It may still DISPLAY it at the same size, but this would just mean that the zoom level has now changed. IE, before the crop the zoom may have been 50 percent (larger picture) and after the crop it is now 75 percent (smaller picture, not as much zoom needed to display the same size.)
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  • StevenVStevenV Registered Users Posts: 1,174 Major grins
    edited January 27, 2006
    Rhuarc wrote:
    Does teh crop tool in photoshop really cause it to interpolate data?
    It sure appears to.

    If I use the marquee set to fixed aspect ratio of 5x7 and Image->Crop, I end up with one size (216px by 154px in what I just did).

    If I select the crop tool and set it to 5in x 7in x 100dpi, use it to select exactly the same area then look at image size, the result is 500px by 700 px.

    If I select the crop tool and set it to 5in x 7in x 300dpi, use it to select exactly the same area then look at image size, the result is 1500px by 2100 px.

    To me it looks like there are pixels being created.
    -Steven
    my words, my "pro"pictures, my "fun" pictures, my videos.

  • colourboxcolourbox Registered Users Posts: 2,095 Major grins
    edited January 27, 2006
    Actually, the Crop tool doesn't always interpolate, but it usually does. It's not easy to identify the cases where it won't interpolate, which is why it's easier to use the marquee when you need to crop to pixel dimensions without interpolation. The marquee guarantees that you select the specified pixel area, and doesn't interpolate when you do Image > Crop.

    If you have a 400x300 pixel image and you want to crop to 300x200, and you don't want any interpolation, and you want to use the Crop tool, you have only two choices that I know of:
    A. Don't enter any dimensions or dpi in the Options bar, and watch the Info palette, with units set to pixels, to monitor the size of your crop, and let go when the Info palette W and H say 300 x 200. The Crop tool doesn't interpolate when the Options bar is blank.
    B. Enter 300x200 into the Options bar, but be very careful to drag a Crop rectangle that is exactly 300x200 (again, monitor this in the Info palette). If you enter 300x200 in the Options bar but you drag a rectangle that is even one pixel larger or smaller, it will interpolate whatever you selected to 300x200.

    To keep life simple, I use the Crop tool when I either want interpolation or I don't care, and I use the Marquee tool when I don't want any interpolation at all.
  • digismiledigismile Registered Users Posts: 955 Major grins
    edited January 28, 2006
    Rhuarc wrote:
    Does the crop tool in photoshop really cause it to interpolate data?

    Depends. Yes, if you have something filled in the resolution box. No, if you leave it blank. I use the crop tool all the time to select an area and through the rest away without any interpolation.
    Brad

    www.digismile.ca
  • bhambham Registered Users Posts: 1,303 Major grins
    edited January 28, 2006
    digismile wrote:
    Depends. Yes, if you have something filled in the resolution box. No, if you leave it blank. I use the crop tool all the time to select an area and through the rest away without any interpolation.

    I use the crop tool almost always but don't put in a resolution. Thus is doesn't add or delete any info that is in the selected area.

    If I then decide I need to upsize or downsize I do that in a seperate step. Down with crop, up with GF.
    "A photo is like a hamburger. You can get one from McDonalds for $1, one from Chili's for $5, or one from Ruth's Chris for $15. You usually get what you pay for, but don't expect a Ruth's Chris burger at a McDonalds price, if you want that, go cook it yourself." - me
  • RhuarcRhuarc Registered Users Posts: 1,464 Major grins
    edited January 29, 2006
    bham wrote:
    I use the crop tool almost always but don't put in a resolution. Thus is doesn't add or delete any info that is in the selected area.

    If I then decide I need to upsize or downsize I do that in a seperate step. Down with crop, up with GF.

    Do you really lose quality if you do a normal crop with the crop tool letting Photoshop interpolate to a given resolution?

    In my workflow I:

    Open the JPEG from my camera in photoshop
    Make any changes
    Use the crop tool (default settings, default resolution)
    Save either as JPEG, or as PSD if I'm kaing more changes.

    When I open my files from my camera they open with a given resolution. In my case they usually open at 72 ppi. But when I print the program automatically increases the resolution as it reduces the size of the picture until it reaches the size of the print I want correct?

    Man, I wish there was a clear explanation of how Photoshop handles resolution and such!
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  • StevenVStevenV Registered Users Posts: 1,174 Major grins
    edited January 29, 2006
    Rhuarc wrote:
    Do you really lose quality if you do a normal crop with the crop tool letting Photoshop interpolate to a given resolution?
    as others have said, "it depends." On what? As far as I can tell -- and if other more expert folks know differently please correct me here -- the answer is: on what's already there and what you're asking for. What matters is the total number of pixels (dots) that it needs.

    If you're selecting an area that has 800x600 pixels and you're asking for more pixels than that, it's got to add some. If you select that area and ask for less than that, it throws some away.

    It doesn't matter if "what you're asking for" is 8"x6"x100dpi or 4"x3"x200dpi, you're asking for 800x600 pixels.

    If you select that same (currently 800x600 pixel) area and ask for 8"x6"x300dpi, it's got to add some pixels.

    If you select that same (currently 800x600 pixel) area and ask for 4"x3"x100dpi, it throws some pixels away.

    Given this whole thread, I'm looking at changing my workflow a bit, changing my "crop" stage from "Use the crop tool" to "Use the marquee tool" so I can be more sure I'm not creating/removing any data.
    bham wrote:
    If I then decide I need to upsize or downsize I do that in a seperate step. Down with crop, up with GF.
    What's GF?


    icon_pirate.gif
    -Steven
    my words, my "pro"pictures, my "fun" pictures, my videos.

  • bhambham Registered Users Posts: 1,303 Major grins
    edited January 29, 2006
    GF = Genuine Fractals.
    "A photo is like a hamburger. You can get one from McDonalds for $1, one from Chili's for $5, or one from Ruth's Chris for $15. You usually get what you pay for, but don't expect a Ruth's Chris burger at a McDonalds price, if you want that, go cook it yourself." - me
  • Art ScottArt Scott Registered Users Posts: 8,959 Major grins
    edited February 11, 2006
    bham wrote:
    GF = Genuine Fractals.

    Is GF truly worth the money? ne_nau.gif

    I have googled for interploating comaprisons and all are very old.....back when GF was at around 2.0.

    I see that Fred Miranda says his SI Pro is better than GF. ne_nau.gif

    I see 40 X 60's produced from nikon D1's, and they were 2.74 MP (and no pixelateing) ..... and I want to be able to that with my 6 & 8 mp cameras.


    Any answers out there?ne_nau.gif
    "Genuine Fractals was, is and will always be the best solution for enlarging digital photos." ....Vincent Versace ... ... COPYRIGHT YOUR WORK ONLINE ... ... My Website

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