Results 1 to 6 of 6

Thread: Digital enlargements

  1. #1
    Photographer; for hire!! shiato storm's Avatar
    Join Date
    Aug 2003
    Location
    next door
    Posts
    6,977
    Thanks
    4
    Thanked
    6 times in 5 posts

    Digital enlargements

    Right, as many of us know the more 'reachable' digital SLRs have 6 or 8 megapixels. in order to do any enlarging (from what ever file type but preferably RAW) above a respectable 10x8 or so it requires some clever trickery so as not to lose any quality i.e. loss-less enlargements. I'm not fully clued up on this but basically you can get plug-ins (photoshop) or specific software to increase the size of the image without quality loss, sort of filling in the pixels going beyond what a simple enlargement does...
    Anyone know whats the best to use as I'm aware there are a few out there? I just dunno what they're called or how good they are
    Powered by Marmite and Wet Dog
    Light Over Water Photography

  2. #2
    I eats food da_ging's Avatar
    Join Date
    Jul 2003
    Posts
    2,256
    Thanks
    10
    Thanked
    29 times in 24 posts
    • da_ging's system
      • CPU:
      • E5200 @ 3.75Ghz
      • Memory:
      • 4GB kingston HyperX 8500
      • Storage:
      • 2*WD640gb in Raid 0 +500gb 32mb seagate
      • Graphics card(s):
      • BFG GTX 260 Maxcore OC2
      • PSU:
      • Corsair 650w TX
      • Case:
      • Stacker 831 black
      • Operating System:
      • XP Pro
      • Monitor(s):
      • 23" fujitsu 3230t LCD 1920*1080
      • Internet:
      • 8mb
    i find the built in resizing works fine , you can get a plugin called Genuine Fractals (i think) but it was no better than the bi-linear resizing that psp 8 has built in , some people also say it is best to enlarge 10% at a time instead of 1 large 30 40 or whatever % jump

    just found this and it may be of interest
    http://www.fredmiranda.com/SI/index.html
    Last edited by da_ging; 13-02-2005 at 11:29 PM.

  3. #3
    Senior Member
    Join Date
    Mar 2004
    Location
    Cork
    Posts
    1,467
    Thanks
    0
    Thanked
    0 times in 0 posts
    Interesting . I never really thought much about this before.

  4. #4
    Photographer; for hire!! shiato storm's Avatar
    Join Date
    Aug 2003
    Location
    next door
    Posts
    6,977
    Thanks
    4
    Thanked
    6 times in 5 posts
    yeah, i read somewhere you can enlarge as per-normal in PS but you lose quality. this interpolation thing resolves it and means you can blow a 6megpix image upto life size or beyond...
    Powered by Marmite and Wet Dog
    Light Over Water Photography

  5. #5
    Admin (Ret'd)
    Join Date
    Jul 2003
    Posts
    18,481
    Thanks
    1,016
    Thanked
    3,208 times in 2,281 posts
    Quote Originally Posted by shiato storm
    yeah, i read somewhere you can enlarge as per-normal in PS but you lose quality. this interpolation thing resolves it and means you can blow a 6megpix image upto life size or beyond...
    All interpolation is is a mathematically based guess.

    Suppose you were monitoring the speed of a car, and had readings taken every minute, from minute 1 to 5 inclusive, and they were 10mph, 20mph, 30mph, 40mph, 50mph, respectively.

    If you wanted to know the speed at 2 minutes 30 seconds, a simple interpolation would suggest that, since the 'function' is a straight line, the value at 2 mins 30 would be 25 mph.

    However, you only have limited data samples. Suppose the car had actually accelerated to 20 mph, then held that speed exactly for 45 seconds, then accelerated again so that it was doing 30mph when the 3 minute reading was taken.

    Your 'interpolated' speed would be 25mph, buit the actual speed was 20mph.


    This is, obviously, a simplistic example but the principle applies to images, too. Interpolation looks at the surrounding pixel data, and "invents" new pixels based on that data.

    Sometimes, that invented pixel will be absolutely right. If you have a large block of solid black in a corner, and you enlarge the image using interpolation, it seems reasonably likely that setting the interpolated pixels to solid black would give the same results from interpolation that you'd have got had you taken a higher resolution image in the first place.

    But what if two adjacent pixels are different colours? If one was black and one was white, a simple interpolation would suggest an invented pixel in-between would be mid-grey.

    Of course, actual interpolation algorithms are FAR more complex than that in operation, but the principle never alters .... interpolation increases the resolution by adding in 'invented' pixels to the actual image data. There will, therefore, inevitably be some loss of image quality. The question is how much? And can you see it?

    Different algorithms (and tools) work in different ways and some even suit some images better than others. I have yet to find a convincing argument that a given tool, or a given set of settings, is ALWAYS going to produce the best results.

    My criteria has always been to assess whether a given method gives results that are good enough. And that is subjective. For instance, the human eye is better able to pick out lost fine detail when viewed close up. So if you heavily interpolate an image and crop to print at 6x4, people will probably be holding it in their hand when they look at it. If, on the other hand, you print at 20x16, the likelihood is that the image will be hung on the wall and viewed from several feet away, and fine detail isn't so obvious then. So, a level of interpolation that I would not find acceptable in a 6x4 print might well be acceptable if it's in a 20x16 print hung on a wall.

    On the other hand, it may also depend on the wall it's hung on. What looks OK hung on the wall in your hallway might very well be far from acceptable as an entry in a your local photo society annual competition.

    It is, as they say, all in the eye of the beholder.

  6. #6
    Senior Member skuzgib's Avatar
    Join Date
    Oct 2004
    Location
    Bromsgrove, Worcestershire / Durham
    Posts
    1,917
    Thanks
    6
    Thanked
    1 time in 1 post
    http://www.trulyphotomagic.com/short...uct_serie_info

    This is good for resizing images - I've had good results with it.

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. How Digital Audio works
    By Lowe in forum Audio Visual
    Replies: 23
    Last Post: 12-04-2013, 09:16 AM
  2. Is this a digital TV?
    By ajbrun in forum Consumer Electronics
    Replies: 22
    Last Post: 29-12-2004, 08:27 PM
  3. 3.5mm digital out to digital coax in on a decoder?
    By Alex in forum Consumer Electronics
    Replies: 3
    Last Post: 17-03-2004, 07:43 PM
  4. New digital camera?
    By streetster in forum PC Hardware and Components
    Replies: 15
    Last Post: 26-12-2003, 01:29 AM
  5. Audigy 1 Digital Output
    By Zak33 in forum PC Hardware and Components
    Replies: 0
    Last Post: 23-08-2003, 07:16 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •