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Thread: Changing image sizes do you resample? PS7

  1. #1

    Default Changing image sizes do you resample? PS7


    Would like to know a couple of things in Photoshop 7.

    1) Is it always 72 dpi whenever you download your pictures?

    2) When you change image size to 300 dpi for print, do you resample the image and constrain the proportions (i constrain them for fixed 4:6 4R prints)

    2i) What happens when you dont resample? The image gets smaller and thus the resolution on print gets worse?

    2ii) i cannot remember what i did, i did not resample for my previous batch and the pics turned out quite bad on print.

    3) An example from the image size info from my previous batch:

    Pic Dimension 5.49 m
    Width: 1200 pixels
    Height: 1600 Pixels

    Document size
    Width: 423.33 mm
    Height: 564.44 mm
    Resolution: 72 pixels/inch

    I cropped (first) then resized image to 300 pixels/inch (should i resize first then crop?) and got these:

    Pic Dimension: 2.66 m
    Width: 787 pixels
    Height: 1181 pixels

    Document size
    Width: 66.63 mm
    Height: 99.99 mm
    Resolution: 300 pixels/inch

    Notice the huge decrease in pic dimension. I believe in this way the image just got smaller instead of richer in resolution.


    Last time i printed great pictures. Sharp and lots of info. I might have screwed up my process due to losing touch with PS7. Kindly tell me how (i really am stumpped ) i got from this:

    Pixel Dimension: 9 m
    Width: 2048 pixels
    Height: 1536 pixels

    Document size
    Width: 289 mm
    Height: 216.75mm
    Resolution: 180 pixels/inch

    TO THIS:

    Pixel Dimension: 6.32 m
    Width: 1820 pixels
    Height: 1213 pixels

    Document size
    Width: 76.2 mm
    Height: 50.79mm
    Resolution: 606.667 pixels/inch

    NOTE: 76.2 / 50.79 = 1.5
    which is 3 / 2

    You see everytime when you crop the image or adjust image size either the proportions get constrained for 3:2 (at least for the instance above) or the resolution is set for example at 300 pixels/inch. In this instance, it is perfect 3:2 ratio but the Document Size looks unmanipulated. Just wondering how i got it resized hee hee. Please help me solve this little mystery of mine. All pics of my previous batch are of this nature.

    Thank you so much for this reading this junk, i am very frustrated trying to figure this out. So any little help will be greatly appreciated!!!


  2. #2


    That's a long one tho,

    Guess you are somehow getting confused about dpi and ppi.

    Pixels per inch (ppi) are generally refering to the number of pixels displayed per unit of printed length in an image, where Dots per inch (dpi) refers to the number of pixels or dots displayed perunit of length on the montor, which depends on the size of the monitor plus its pixel setting. Most monitors have a resolution of about 72 dpi, or 96 dpi on the newer ones.

    Image pixels are translated directly into monitor pixels, meaning that when the image resolution is higher then the monitor resolution, the image appears larger on-screen than it's specified print dimensions. For eg, when you display a 1-by-1 inch, 144 ppi image on a 72 dpi monittor, it appears in a 2 by 2 inch are on-screen. Since the monitor can only display 72 pixels per inch, it will needs 2 inch to display the 144 pixels which is one small portion of the image.

    In photoshop, image resolution and pixel dimensions are interdependent. The amount of detail in the image resolution controls how much space the pixels are printed over. You can modify an image's resolution without changing the actual pixel data in the image, you only change the printed size of the image. If you want to maintain the same output dimensions, changing the image's resolution requires a change in the total number of pixels.

    Resampling, changes the pixel dimensions of an image. when you downsample, you decrease the numbers of pixels, where information is deleted from the image. On the other hand, when you resample up, you increase the number of pixels, where new pixels are added on the colour values of existing pixels. Note that resampling might result in poorer image quality, esp when you resample an image to larger pixel dimensions, the image will lose some detail and sharpness, might need to apply the USM filter.

    Hrm, if you turn on resampling for the image, you can change print dimensions and resolutions independently. When it's off, you can change either the dimensions or the resolution, where photoshop will automatically adjust the other value to preserve the total pixel count. For the best print quality, read somewhere it's generally best to change the dimensions and resolution first without resampling, then resample only as necessary.

    Alternatively , you can play around the scale by using The Print with Preview command, changes made affects only the printed image, not the document size of the image file.

    Hope this helps.

  3. #3


    Wow a very concise and enlightening reply. Thank you very much.

    Now i can recall more of what i had learnt before...Thanks!!

  4. #4


    No problem.


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