Resizing Photos with out loosing pixels?

Discussion in 'Digital Photography' started by imac abuser, Sep 14, 2006.

  1. imac abuser macrumors 6502a

    imac abuser

    Joined:
    Mar 1, 2004
    #1
    Hello,
    I have Adobe Photoshop CS, and Aperture. I want to know how I can crop a picture in the correct dimensions so when I print a 4x6 it's not all pixelated, or grainy.

    Chris
     
  2. ChrisA macrumors G4

    Joined:
    Jan 5, 2006
    Location:
    Redondo Beach, California
    #2
    There is no way to crop an image and not loose the pixels you crop off. It's not a matter of technology it is a matter of logic: Cut anything in two, throw away one part and you will have less of what you had. Basic logic, no way around it. Technology can't help you.

    So you have less pixels. What to do? You could "resample" the image. This process will creat pixels by interpolation and will cure the pixelation problem but resampling does NOT creat more infomation the overall effect is to blur the image. The effect is the same is taking off your glasses and looking at the pixelated image.

    There is a rule of thumb. For 4x6 prints of best quality you need about 300 pixels per inch. that means for the 4x6 size 1200 x 1800 pixels if you have a 6MP DSLR that shoots 3000 x 2000 frames then you have only a little room to crop before you break the 300 per inch rule. You can reduce the rule to 240 or even less. Newspapers print at about 75 per inch. But you are seeing the results in your work of grossly violating the 300 pixels per inch rule -- quality suffers. resampling can help mask theses effects but the result is an unsharp print.

    The best thing of course is to use your feet and get closer to the subject. Look all around the edges of the frame to make sure there are not unwanted objects in the frame and _then_ trip the shutter. If you do this then there is less need to crop.

    After you take the shoot LOOK at it. If it will require a crop walk forward a bit and take another shot. If there is a physical bearier such as a fence, rail, water or a cliff then you must resort to using a longer telephoto lens but you will always get the beter result if you can use your feet.
     
  3. imac abuser thread starter macrumors 6502a

    imac abuser

    Joined:
    Mar 1, 2004
    #3
    Thanks for the info, I don't mean to sound like a dork. I didn't mean keeping the pixels I'm cropping off. I just meant how can I crop a picture, and keep it in the proper aspect ratio for a 4x6 or whatever with out pixelation, or grain in the print.
     
  4. timnosenzo macrumors 6502a

    timnosenzo

    Joined:
    Jun 21, 2004
    Location:
    ct, us
    #4
    In Photoshop, when you're using the Crop tool you can click the "Front Image" button on your toolbar, so it will maintain the images size. Is that what you're looking for?

    Picture1.jpg
     
  5. Josh macrumors 68000

    Josh

    Joined:
    Mar 4, 2004
    Location:
    State College, PA
    #5
    Make sure you're image is at the correct resolution for print.

    Click "Image --> Image Size" and make sure it is 4x6 " at 350dpi.

    If it is at 72dpi (common screen resolution), it will look very pixilated when you print.

    However, with the majority of photosizes around today, you should be getting sharp 4x6's if the resolution is set high enough.

    Look at the settings in photoshop I've attached below (it's Windows, but the dialog is the same). Make sure your image's resolution is not 72 pixels/inch.
     

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  6. ChrisA macrumors G4

    Joined:
    Jan 5, 2006
    Location:
    Redondo Beach, California
    #6

    You can set the pixels/inch as high as you wish. But if you start with a 600x400 section cropped from the center of your camera's ful image the results will not be good. It will not look "blocky" or "pixelated" but it will be very unsharp. Like I said above resampling will mask the problem. The basic rule is that you MUST have enough pixels in the source material for the print size you want. No way around that basic fact.

    This is not speciifc to digital photos. If you used a 35mm film camera and took (say) a group photo of 12 people. Then later wanted an enlargment where you took just one of the faces and blew it up to an 8x10 size the result would be grainny and blurred.

    The above is the best you can do, tell photoshot to resample the cropped image to (about) 300 pixels per inch and PS wil resample the image. But PS is not magic andit can't create details that are not recored by the camera
     
  7. stearel macrumors newbie

    Joined:
    Mar 30, 2004
    #7
    imac abuser, you seem to be asking two questions:

    1. How do I crop keeping a specific aspect ratio?
    2. How do I crop without making the image pixelated when printing?

    Question 2 has been answered, and Question 1 has been answered for Photoshop. Here is Aperture:

    1. In Aperture, use the cropping tool (by pressing "C" on the keyboard), and make sure that you have the "Constrain cropping tool to common sizes" selected. Use the drop down menu to select your desired common size (6 x 4 or 4 x 6 in your scenario)
     

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  8. Josh macrumors 68000

    Josh

    Joined:
    Mar 4, 2004
    Location:
    State College, PA
    #8

    That's true, but it's also very unlikely that with today's consumer digi cams (and even scanned 4x6's) that a cropped image is going to be so small at 72dpi (as I've stated in the post).

    Take an 8x10 from a 6mp camera and print it at 72 dpi and it's going to be rubbish.
     
  9. imac abuser thread starter macrumors 6502a

    imac abuser

    Joined:
    Mar 1, 2004
    #9
    Thanks guys stearel your the man that's kinda what I wanted a way to take a fullsize image and kinda have a 4x6 template or cookie cutter lol to make a 4x6 crop out of a full size image
     

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