Image Size question

Discussion in 'General Technical Discussion' started by kccheers, May 8, 2005.

  1. kccheers

    kccheers

    70
    May 2, 2005
    Liberty, Mo
    I have an Image size question:

    I am fairly new to the D70, and we took quite a few pix on vacation last fall in Estes Park. I shot jpeg and the file size for the images was
    3008x2000. I know I can resize the pic to make the file size smaller, but if I crop it and the image changes because of the crop, if I get a print made will it have white borders possibly on 2 sides instead of a full print?

    I guess my basic question is this: Is the 3008x2000, or similar resized file the default for a "print" size file, where the entire photo paper would be filled? Is there a formula to this, such as 300x200, etc?

    Thanx for the help.

    cheers from KC
     
  2. Gale

    Gale

    978
    Jan 26, 2005
    Viera Fl
    Guess you need to tell the forum what program (s)you are using to edit :>))
     
  3. kccheers

    kccheers

    70
    May 2, 2005
    Liberty, Mo
    Sorry, that would be Photoshop 7.0
     
  4. Gale

    Gale

    978
    Jan 26, 2005
    Viera Fl
    Hi Sam,

    I had a hard time with this also. Thank God I have a local printer that does everything for me and will even do some touch ups.

    He showed me.

    At the top of the window when you choose the crop tool,

    Put in the sizes, ie: 5x7 or 7x5, 8x10, 10x8, at 300 You know your oriientation, landscape or portrait.

    Drag the mouse from the corner, until it stops within the size range. THENNNNNNNN

    you will prob have to crop. In the center of that area, before you chose crop you can move it around where you want it. Just put your mouse in the middle and you can move it around. Must stay within the pic perimeters tho.

    ORRRRR sometines what I have to do is crop first just how I like the pic, and then put in the parameters. Before you do it that way hit the clear button on top to clear your previous demensions.

    Then go back after YOUR personal crop and re-enter your sizes..

    You may find you chopped off to much , then you must start over.

    If you did not crop off to much try the sizing again and you may have a little you may have to still crop off.

    The smaller you print the more comes off. I don't usually loose to much . I only have printed, at the printers 8x10 or larger.

    For my little album, 5x7 I will lose some. Put on a disk and take to the local keiosk and print my own in the machine.
    I don't know if this is right or not. But you can give it a try until some gurus come by.

    Let me know.

    If there is a better way I would like to know also.

    My printed pics are always perfect, from the printer.

    PS: Remember when you get something you don't like go to edit and stepback , or undo crop, Or you can use ctrl z.
     
  5. Sam,

    As you can see, 3008x2000 is an almost perfect 3 by 2 aspect ratio (3000x2000 would be perfect). That aspect ratio is common in photography, and is also used in 35mm film, where the exposed area of a frame is 24x36mm.

    Unfortunately, other than 4x6 (inches), the common print size do NOT include that aspect ratio: 5x7, 8x10, 11x17 (that one is close), 13x19 (also close) etc... are all using different ratios of width to height. To print in those "standard" dimensions, some amount of cropping is always necessary.

    The number of pixels needed is obtained by multiplying the chosen print resolution (say 200 or 300 dpi) by the print size you want: so for a 5x7 at 200dpi, you would need 1000x1400 pixels. For an 8x10 print at 300dpi, you need 2400x3000 pixels, wich the camera can't produce directly, so one uses interpolation (or resampling) to create more pixels from their neighbors. I hope this helps.
     
  6. kccheers

    kccheers

    70
    May 2, 2005
    Liberty, Mo
    Thanx to both Gale and Phillipe. You guys answered my main question well. I suppose most of these answers are probably in the Help section of PS, I just thought I wouild try for a real world explanation. And, I got it!

    One more quick question. While taking pix in large file size, whether jpeg, tiff, etc, what is the optimum file size to copy down to for posting on the web, let's say with Smugmug, for example. Then is there a way to resize an entire batch of pix instead of one at a time?

    cheers from KC
     
  7. kccheers

    kccheers

    70
    May 2, 2005
    Liberty, Mo
    Phillipe, could you also give me a quick study for what "resampling" is that you spoke of?

    Sam
     
  8. Sam,

    The term sampling in anything digital means to convert an analog (continuous) signal or information into a descrete (numeric) set of data values, representing the original analog signal.

    When changing the scale of the representation, one can convert a set of samples (numeric values) to another set, by resampling. This involves complex math and what not... but it basically means that data that was not really there (sampled) the first time, get created by the resampling process. This mechanism is also known as interpolation.

    Interpolation/resampling is what happens when you blow up or shrink a picture. For instance, it is easy to conceive that if you reduce an image by 2 in each dimension (making the total area 4 times smaller), this can be accomplished by replacing every square of 4 pixels by a single one, taking the average color of the 4 that were there before it. But if you change the percentage of reduction from 25% to say 43%, things are not so simple any more...

    Resampling works in the other direction too: to increase the number of pixels a picture has: a naive approach to blow up a picture by a factor of 4 (twice in each dimension), is to duplicate every pixels in each dimension. This does not create *new* information: it justs changes the representation of the existing one. This process (or things much more complicated, needed to preserve as much visual quality as possible) is what allows PS and all the other picture software programs to shrink and blow up the pictures. Look at the help that comes with PS and type in resampling in the search box: you'll see an interesting explanation and example.

    By the way, printers do this internally too, to adjust the number of pixels that the software delivers to them to a number of dots that the heads can send ink to.
     
  9. Sam, re: your question of the optimum size for the web. First, there is often confusion about image size in terms of pixels or file size in terms of bytes.

    First let's talk pixels. The typical computer monitor displays at around 72 pixels per inch. Without resizing, your 3000 (wide) pixel image would be almost 42 inches wide. Each forum usually has pixel restrictions in the neighborhood of 650-950 pixels in width (or what would appear as 9-13 inches wide on the screen.) Anything larger than this causes a viewer to have to scroll side-to-side to see the whole picture. You adjust this in PS with the Image Size dialog box. I'm not familiar with smugbug, but pbase places no restrictions on file size. I sometimes upload two images to pbase - one to be viewed there at a large size and a smaller one for purposes of linking to forums like this one. Some hosting sites like Imagestation impose their own templates on your images whether you like it or not.

    After resizing, your image is still packed with a lot of data and may be several hundred kilobytes in file size. This would work as is, but the time needed to download the image for viewing might be unacceptable - especially for those with dial-up. Most forums limit the size of files to reduce the burden on their server (and the costs of operation). When you save your resized image in jpeg, you control the size of the file by choosing the amount of compression. This is where the trade-off happens. To get a file down to an acceptable size, you have to get rid of data in the compression process. Sometimes this results in jagged edges or halos if too much compression is applied. Usually, keeping the file size to less than 100KB is a good compromise. Some images can go much smaller without showing any degradation and some can't. It depends on the complexities in the image itself.

    BTW, if PS 7 gives you the option of "Save as..." and "Save for Web", choose the web option. Using this option strips the exif information from the file and lets you get more image data into any given file size.

    Sorry, but I can't help you re: resizing in batches. I'm still a one-at-a-time processor.

    Hope this helps.
     
  10. Gale

    Gale

    978
    Jan 26, 2005
    Viera Fl
    PS: I am sure you know. But never work on your original. Always a copy of it.

    I goofed a couple times.
     
  11. kccheers

    kccheers

    70
    May 2, 2005
    Liberty, Mo
    Thanx John. And PS7 does have the "save to web" option. Man, that's why I am here. There are so many very kewl people here who share the same passion, albeit in different levels of knowledge, but.....we all start somewhere! Thanx again.

    BTW, I am originally from Alvin, Texas, so we are kinda ex neighbors, I guess......

    cheers from KC
     
  12. Alvin...that's Nolan Ryan's home town, isn't it?
     
  13. Various Thoughts

    I NEVER 'save for web' in PS. I don't like what it looks like. I prefer to resize in the Image Size command and then 'save as' to jpg.

    By the way...if you shoot in jpg and plan to work on it in PS then first save it as a tiff or a psd file. You don't want to resave a jpg.

    The Image Size menu item gives you different resizing options. To downsize (down sample) use Bicubic Sharper, to up size use Bicubic Smoother.

    Always sharpen AFTER you resize.

    For the web I always convert to 96 ppi. I usually try to get it about 800-900 pixels for the longest side.
     
  14. Chris101

    Chris101

    Feb 2, 2005
    Arizona
    Heh - good one! :) :) :)

    Or maybe I ought to try reading instructions once in a while... ?? ;)
     
  15. kccheers

    kccheers

    70
    May 2, 2005
    Liberty, Mo
    instructamacationz......now where is that key......


    Hey tex, yea, it's NR's home town. Super cool guy. When I was growing up he was our paperboy. Then he grew up, found girls, and married a good friend of mine's sister, Ruth. Just a normal guy to hang with, likes all the normal things we all did.....oh, but maybe he saw the Devil from the mound???? I would not have wanted to bat against him even in LL. We watched him in High School. Man was he wild!

    cheers
     
  16. hawkbug

    hawkbug Guest

    For sizing images for the web you might want to try the "Web Presenter Plugin" by Fred Miranda. It's available as a Photoshop plug-in for the PC or Mac and cost $19.90. Here's the link for the PC version: http://www.fredmiranda.com/shopping/WPpro

    As a web designer I am constantly resizing photos but was never really happy with the results before using the Web Presenter Plugin. It's a truly amazing product that saves me hours of USM work.

    Hawk
     
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