Digital image resolution?

Discussion in 'Beyond the Basics' started by Ant, Jun 20, 2004.

  1. Ant

    Ant TPF Noob!

    Joined:
    Jun 2, 2004
    Messages:
    438
    Likes Received:
    3
    Location:
    Luton. UK.
    My digital camera has 23 different photo resolution options :shock: Which means that I find getting the right balance between image quality and number of shots on the media card to be quite a bewildering choice..

    I've narrowed my options down somewhat through experience but there's one thing that's confusing me a bit: Is it better to have more pixels at a higher JPEG compression or less pixels at a lower compression?

    I've just done a quick little test - I've taken a pic at 4 MP resolution with normal JPEG compression and the same pic at 2MP with very low compression. The 4MP photo comes out at a size of 810KB and the 2MP photo comes out at a size of 1233KB...much larger, which suggests to me that the 2MP photo should be better as there's more image info. However, when I look at the two on my monitor the 4MP pic actually looks better. This leads me to believe that more pixels is preferable to lower compression....What are your views on this?

    I'm mainly interested in viewing photos on the PC rather than printing them, but if I did decide to print would the JPEG compression levels be more of a factor for hard copy quality?

    Sorry for the long rambling post but this has been bugging me for a few days now.
     
  2. photobug

    photobug TPF Noob!

    Joined:
    Apr 19, 2003
    Messages:
    1,562
    Likes Received:
    4
    Location:
    Pasco, WA
    If you needed to make a copy of a letter on a copier and you had an original and a 4th generation copy of the letter... which one would you run through the copier?

    You can copy the copy of the copy of the copy ad infinitum to degrade the quality, but you can't get back to the original quality after you do it.

    So, in a round about way I'm saying- you can't put back into a pic what isn't there. If you start with less info (# of pixels) in a pic it ain't never gonna get any better than it is.

    Someone on another photo board uses the following tagline- Shoot RAW. Because memories are priceless, but memory is cheap.

    What he's saying is you can do anything with a high resolution original, including resizing it to postage stamp size, and anything in between.

    But if you have a postage stamp to start with it'll never be anything (worth viewing) but a postage stamp. No matter how big you wish you could print it.

    Sorry for the long rambling answer to your long rambling post. ;)
     
  3. Ant

    Ant TPF Noob!

    Joined:
    Jun 2, 2004
    Messages:
    438
    Likes Received:
    3
    Location:
    Luton. UK.
    Well RAW isn't an option for me, unfortunately, as my camera doesn't do it....TIFF is the highest uncompressed resolution. I probably wouldn't know what to do with RAW anyway :)

    Also memory isn't that cheap, a 256MB XD card will cost me about £75 ($137) and at highest quality I'd only get 20 shots :( which isn't really always practical if you're going out on a day's shooting. I understand the sentiment of shooting at highest quality but from a practical point of view it's not always realistic. Also I'm pretty much just a P&S guy so I'm not really doing anything too fancy or artistic.

    Essentially, in my world of compromise I just want to know if more pixels are better than lower compression or the other way round? :)
     
  4. StvShoop

    StvShoop TPF Noob!

    Joined:
    Jun 9, 2004
    Messages:
    449
    Likes Received:
    0
    Location:
    Troy, NY
    the effect of compression depends on what is in the image. When i do the "save for web" thing in photoshop, and drag the slider for jpeg compression around, i've noticed that some shots look almost perfect at 50% compression, while others don't look good unless they're less than 12% compressed.
    I'm not really sure how jpeg compression does what it does, so all i can do are give examples. shots of telephone poles + wires with a bright blue sky behind them tend to need low compression, or the area next to the wires gets hazy really fast. It seems like the ones that do best under compression are photos of low to medium contrast with little textural information (pretty boring photo :p )
    if you're mostly viewing on the computer (like me!) you realistically don't need more than 2.5 megapixels, something like that. UNLESS you want to crop something that's small in the image, UNLESS you decide one day years down the road that you need a print of an image, etc.
    there's no one correct answer. i just got a new 128mb card (for only $25 on amazon, you should check on that) and i'm still working out how to manage long photo trips away from my computer. at 3.2mp, it's running out of room more quickly than i had hoped.
    my tendency (only when i have to) is to go with less pixels and less compression, because compression is "iffy" as to what information gets messed up/left out
     
  5. photobug

    photobug TPF Noob!

    Joined:
    Apr 19, 2003
    Messages:
    1,562
    Likes Received:
    4
    Location:
    Pasco, WA
    Well, like I said, you can't put back what isn't there. The more info a pic contains, the better looking it'll be (compression aside). You have to decide what level you're comfortable with for your usage.

    In other words- I can't answer that. I can tell you what I'd do- shoot the most pixels I could, but that obviously isn't going to match what you need.

    How many pics do you usually shoot in an outing? How many do you end up keeping? That should help you answer what settings you should be using.
     
  6. Ant

    Ant TPF Noob!

    Joined:
    Jun 2, 2004
    Messages:
    438
    Likes Received:
    3
    Location:
    Luton. UK.
    Yeah, I suppose it's all about personal choice really. I was just surprised that I found the image that was smaller to be better looking than the image that had more info. Maybe I'll try printing some out and see how they translate to hard copy.

    Good point about the amount of pics I take compared to how many I keep. I tend to be a bit snap happy but only end up with a few good ones and the rest are pretty so-so. Maybe a bit more discretion in future would be better :) and also allow me to shoot at higher resolutions.
     

Share This Page