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  1. #1
    Platinum Lounger
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    Resizing Graphics

    Being pretty ignorant in this area, I want to know what the best (or recommended) algorithm is when resizing pictures. I've heard of filters like Hermite, Lanczos, Bicubic, Bilinear but don't know much more. I want to incorporate something programmatic, probably in .NET once I find my way around the graphics neck of the woods.

    I'm also wondering what is necessary to produce printer-quality results, as compared with screen quality. Better DPI no doubt, but by what means?

    Alan

  2. #2
    Plutonium Lounger
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    Re: Resizing Graphics

    Hope ya don't mind, Alan, I moved you here for two reasons. The Pix threads expire in 90 days and your question will probably involve discussions of s/w applications best suited for answering your question. I think Pix Place is more suited (intended) for short-term stuff like smilies and the like.

  3. #3
    Platinum Lounger
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    Re: Resizing Graphics

    <img src=/S/yep.gif border=0 alt=yep width=15 height=15> Good "move" <img src=/S/pun.gif border=0 alt=pun width=22 height=18> Al. Something was niggling me about posting it in Pix, but I couldn't think what it was. Must have been a cranius vacuuo moment.

    Alan

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    Super Moderator jscher2000's Avatar
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    Re: Resizing Graphics

    For photos, downsizing with a bicubic algorithm is pretty standard. In Photoshop/PS Elements it is usually best to choose the "Bicubic Sharper" option which helps compensate for some blurring introduced in downsizing. For upsizing, I've read that the Lanczos algorithm is somewhat better than bicubic. But I haven't compared for myself. Perhaps you can check on some photo retouching forums for more "professional" recommendations.

  5. #5
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    Re: Resizing Graphics

    Thanks Jefferson. From what I can gather so far, it's best to retain all the original pixel information, if the graphic is destined for the printer/ publisher, so filters are not appropriate. For screen display though, I think that's where choosing appropriate filters is significant. I've begun reading up on some of this, and it appears that the issues are far from black & white <img src=/S/pun.gif border=0 alt=pun width=22 height=18>.

    Alan

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    Re: Resizing Graphics

    Alan,
    Not sure if this is any use to you, but Irfan View can be run in command line mode from within your own code using the Shell command. <post#=338832 >post 338832 </post#> refers and includes a copy of the command line parameters

    In the past I've used VB to generate the relevant command line parameters to a text file that is saved and passed as a parameter to the Shell command. If you need to resize a picture programatically it can be worthwhile using Irfan View as a tool.

  7. #7
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    Re: Resizing Graphics

    Thanks for that input. I have used IView commandline and batch operations before, and it's very handy for some tasks. In this instance though, I have native code for various specific operations, so will be using that in a standalone application. I really needed some "basics" on resizing for output to printer, and resampling when targetting the monitor screen. Articles such as How much resolution for the video screen? have since set me straight. <img src=/S/grin.gif border=0 alt=grin width=15 height=15>

    Alan

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