Christopher, I managed to get a decent mask but I had to put alot of black around the edges so my image filled the mask (image comes out of a blur patch). I couldn't get the Blend with Mask patch to work in this particular clip, presumably because of a non-(0,0) origin. A very long horizontal strip of 28 images gets cropped incrementally resulting in an image chaser sequence in the main clip. I'm trying to blur this and mask it to use it as a kind of movie projector beam of light.
Using the extra-wide mask I got it to work (and have mixed feelings about the result) but I still have a fundamental ignorance around comping or blending 2 images with non-zero origins. (Hmmm) If you care to look I made a clip in which I substituted a gradient render in image for the large horizontal tiff. You get the idea but it's not possible to see the effects of the resize before and after blurring as the is no image detail. In an aside: Strangely even if I reszie to 10x10 px before the blur and then 200x200 after it seems to regain all the detail that it should have lost. Hopefully 36K makes it through the gate. Thanks for the help Alastair Leith On Wed, Dec 31, 2008 at 12:49 AM, Christopher Wright <[email protected]>wrote: > I am using a 1280x720 black and white image of a triangular-type shape >> which I would l like to mask images generated in quartz. The triangular >> shape is 100% white and the black 0% and at this stage i'm not using a >> gradient for simplicity. The shape is to make a kind of movie projector >> lightbeam throw effect. When I attach the image to the billboard Mask input, >> I don't get a clean edge – the black areas in the mask images show up just >> not as brightly as the white masked areas. I'm looking for a sharp clipping >> mask edge. I tried to workaround with various composite patches (Darken and >> Multiply seemed worth a spin) prior to the billboard (and illiminating the >> need for mask) which only has confused me more and raised more questions in >> regards to matching image dimension (Resize and Crop patches). Because of >> other elements on the screen I'm looking to use Over blending mode. >> There must be a straight forward way to apply an alpha to an image to get >> a clipping mask but i'm from the the land of Adobe products etc, not >> Computer Science, so I'm stumped in QC again >> > > > This seems to work for me -- can you supply some of your content (just the > mask and the composition, no other images required) perhaps, to see why it > isn't masking as expected? (assuming that this doesn't help work out your > problem) > > > > Also on those other question: When hovering the cursor over a patches' >> image output port (not so easy with a tablet BTW Apple) an image preview is >> generated along with dimensions expressed as {a,b,c,d}. c and d seem to be >> the image dimensions but as for a and b they are often negative so are they >> the locating co-ordinates?? If they are, how to get a image matching the >> same location and size as another is beating me also. >> > > Those values express the Origin (x = a, y = b) and Size (width = c, height > = d). The origin is important if you're writing CoreImage Filters, since > many filters will expand an image a bit, causing the origin to go negative. > (There are other reasons why this happens too -- I don't deal with image > processing much, so I can't pencil in many more details of why this is or > why it's important). > > -- > [ christopher wright ] > [email protected] > http://kineme.net/ > > >
image throw (no tiff).qtz
Description: application/quartzcomposer
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