Latest post Thu, Jan 19 2012 11:06 PM by AndrewAction. 5 replies.
Page 1 of 1 (6 items)
Sort Posts: Previous Next
  • Thu, Jan 19 2012 4:38 AM

    • Kale
    • Not Ranked
    • Joined on Thu, Jan 19 2012
    • Posts 10
    • Points 130

    Downscaling graphics look bad, jaggies

    Hi Guys,

    Any help with the following would be greatly appreciated as I have recently jumped ship from FCP to MC 5.5.3

    When graphics are resized to be smaller (50% to 80% original size) there is a very noticeable loss in image quality that takes place. I realize upscaling graphics would result in pixillation, but downscaling shouldn't be a problem should it? At least this was not the case in FCP.

    I've outlined my workflow below. Any thoughts on how to avoid this loss in quality would be great.

     

    Hi resolution jpg (3162x2279 pixels) supplied by 3rd party. taken into photoshop and saved as a .png or .tiff. Then in MC i import the png as a 1:1mxf, options dialog menu: resize image to fit format raster. Time line settings are as follows... Project type: 25i pal, Aspect ratio:16:9, Colour space:YCbCr601(greyed out), Raster Dimension: 720x576.

    If graphics are brought into MC this way and downscaled to fit on an SD time line they look rubbish. I can get around the problem by composing the graphics in photoshop on a SD (1024x 576 square pixels) canvas and brining that into MC and the graphics look great until i need to resize them even a little bit.Obviously this workaround is not ideal.

    I've used various effects to rezise (key matte, Avid fx, 3d warp) all result in the same poor quality. The video quality menu icon is green. Why cant i just downscale like i could in FCP?

    Thanks in advance 

    Kale.

    2x2.4 GHz quadcore Xeon, 24gb ddr3, ATI Radeon HD 5770, OSX 10.6.8

     

  • Thu, Jan 19 2012 10:16 AM In reply to

    • MikeyB
    • Top 500 Contributor
    • Joined on Thu, Oct 13 2005
    • Edlesborough, UK
    • Posts 513
    • Points 6,380
    • Avid Certified Instructors - Video
      Moderator: Avid Certified Instructors - Video

    Re: Downscaling graphics look bad, jaggies

    Hi Kale,

    A few things spring to mind.

    Firstly, you're not downscaling to 50-80% of original size. From 3162x2279 to 720x576 is more like 25% of original size, and I think you will quite likely see artefacts from such a large downscaling, particularly if you're working in a 25i project. The reason is because it's likely that fine details in the original image may become small enough after resizing to be present only on one field of the interlaced frame. This will result in flickering effects when playing the graphic back

    Secondly, even if the above isn't the issue, are you viewing the timeline at full res (green mode)? Graphics will look jaggy in yellow/green mode. Bear in mind also that Avid only outputs Field 1 of the frame to the computer monitor, so you're seeing half res anyway. Mind you, I think FCP does the same.

    Thirdly, unlike FCP, the import process in Avid creates new media at the frame size of the Project - in this case 720x576. Subsequently re-sizing the image with 3D Warp etc is going to soften the image because it's necessarily using the 720x576 downconverted media. You can slightly improve the quality of this by using HQ mode (a button on the Effect Editor toolbar in 3D Warp).

    Fourthly, you can improve the image interpolation by setting your Render settings to Image Interpolation using Advanced Polyphase instead of trhe default Standard Bilinear. Note that this will only affect renders, not real-time playback.

    Finally, an all-round better way to manipulate large graphics is by using either Avid's Pan and Zoom effect or the BCC equivalent, either of which can manipulate the original image rather than the downscaled imported media. I prefer the BCC plug-in for speed of rendering, and it would be my 'weapon of choice' for this sort of thing.

    Hopefully I've hit the mark somewhere with this lot!

     

    MacBook Pro 15" 2016 2.7GHz i7 Radeon 455 [view my complete system specs]
  • Thu, Jan 19 2012 10:22 AM In reply to

    • Lord Fluff
    • Not Ranked
    • Joined on Thu, Dec 15 2011
    • London
    • Posts 112
    • Points 1,445

    Re: Downscaling graphics look bad, jaggies

    There are certain things that FCP handles better than Avid, and stills has always been one of them.

    I would second that you should always use Avid Pan & Zoom, or similar when using stills - quality is maintained and things tend to actually come out the right shape, which is nice Smile

     

    HP z820, Decklink Extreme+, Areca RAID, Artist Colour, Symphony 6 // MBP17, UltraStudio3D, Pegasus TB RAID, MC6 [view my complete system specs]
  • Thu, Jan 19 2012 10:48 PM In reply to

    • Kale
    • Not Ranked
    • Joined on Thu, Jan 19 2012
    • Posts 10
    • Points 130

    Re: Downscaling graphics look bad, jaggies

    Thanks for your time MikeyB,

    Just to clarify a few things. I have the time line set to full res (green mode). i realise that Avid is outputting 1 field (im playing the time line and viewing the output on a monitor, still jaggies.). The downscaling to %80 to %50 of the the original was in reference to my workaround of downscaling in p-shop first to a 1024x576 canvas then brining that into avid.

    Thanks for your suggestions regarding render settings, I'll try these out.

    I've tried using the pan and zoom effect and it works great but can it handel alpha channels? this is a must for my work.

    I have had some success with using the avid fx effect to import and resize images. They seem to scale a lot better. being new to avid,  a good tutorial on using the basics of avid fx would be greatly appreciated. Could you point me in the right direction?

    One again thanks for all your help.

    Cheers,

    Kale. 

  • Thu, Jan 19 2012 10:50 PM In reply to

    • Kale
    • Not Ranked
    • Joined on Thu, Jan 19 2012
    • Posts 10
    • Points 130

    Re: Downscaling graphics look bad, jaggies

    Thanks for the advice Lord Fluff,

    Can avid pan and zoom handel alpha channels?

     

  • Thu, Jan 19 2012 11:06 PM In reply to

    Re: Downscaling graphics look bad, jaggies

    If you have Avid FX then you can "effectively" pan and Zoom from the original tiff with the alpha channel.

    The Boris site also has a tutorial for making vector objects from a jpegs that often gets me better keys and scaling from company logo's supplied on business cards

Page 1 of 1 (6 items)

© Copyright 2011 Avid Technology, Inc.  Terms of Use |  Privacy Policy |  Site Map |  Find a Reseller