April 2009 - Pro-apps-dev - lists.apple.com

Re: FCP Time Remap explained
by Ky Hopwood 30 Apr '09

30 Apr '09

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FCP Time Remap explained
by Paul Stephen Carlin 30 Apr '09

30 Apr '09

site_archiver(a)lists.apple.com Delivered-To: pro-apps-dev(a)lists.apple.com Organization: Spark Media Thread-index: AcnJ2GuTBsyH2EY9SBSp2R9YT1cXnQ== _______________________________________________ Do not post admin requests to the list. They will be ignored. Pro-apps-dev mailing list (Pro-apps-dev(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/pro-apps-dev/site_archiver%40lists.a… This email sent to site_archiver(a)lists.apple.com

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Using GLSL in an FxPlug
by Darrin Cardani 30 Apr '09

30 Apr '09

site_archiver(a)lists.apple.com Delivered-To: pro-apps-dev(a)lists.apple.com Thanks, Darrin -- Darrin Cardani dcardani(a)apple.com _______________________________________________ Do not post admin requests to the list. They will be ignored. Pro-apps-dev mailing list (Pro-apps-dev(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/pro-apps-dev/site_archiver%40lists.a… This email sent to site_archiver(a)lists.apple.com Here's another sample that some may find helpful. It shows how to use GLSL in an FxPlug rather than an ARB fragment program. It's the Brightness example rewritten for GLSL. Thanks to Brian Walsh, one of our engineers in ProApps, for putting this together! GLSLFxPlug.zip As with the other samples, this hasn't gone through a lot of testing, etc., and hasn't been completely cleaned up for the SDK, but I wanted to put it out there for people to see. Let me know if you have any questions.

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Re: Core Image in FxPlug example
by Paul Schneider 29 Apr '09

29 Apr '09

site_archiver(a)lists.apple.com Delivered-To: pro-apps-dev(a)lists.apple.com http://lists.apple.com/archives/quartz-dev/ And of course, the CI documentation: http://developer.apple.com/DOCUMENTATION/GraphicsImaging/Conceptual/CoreIma… Also, the CI Kernel language is documented here: http://developer.apple.com/DOCUMENTATION/GraphicsImaging/Reference/CIKernel… And it is a subset of the GL shading language: http://www.opengl.org/documentation/glsl/ There are lots of GLSL examples floating around out there. - Paul On Apr 29, 2009, at 4:59 PM, Darrin Cardani wrote: vec4 aSample = sample (someSampler, someCoordinates); vec2 coords = samplerCoord (someSampler); kernel vec4 multiplyEffect(sampler someSampler) { // Get the current sampler coordinates vec2 coords = samplerCoord (someSampler); // Subtract 1 from the x coordinate vec2 leftCoord = coords - vec2 (1.0, 0.0); Let me know if that answers your question. Thanks, Darrin On Apr 29, 2009, at 1:15 AM, Brian Gardner wrote: Hi Darrin. Thank you for your examples. Very helpful. Is there any example source code for the Displacement Distortion CI filter which you mention below? Which samples 3 pixels from one image, and 1 pixel from another image? That would be very helpful for me to see. There are very few examples which use multiple (or reference) images, and take multiple samples per image. Is there any such sample code available? (Like of the Displacement Distortion filter you describe, below.) -- Brian On Apr 28, 2009, at 9:01 AM, Darrin Cardani wrote: 0.75 0.89 0.23 0.52 It takes (0.75 - 0.89) = -0.14 as the x offset It takes (0.75 - 0.23) = .52 as the y offset Does that make sense? Darrin On Apr 27, 2009, at 5:53 PM, Patrick Sheffield wrote: Thank you Darrin - this helps a lot. Thanks, -- Darrin Cardani dcardani(a)apple.com _______________________________________________ Do not post admin requests to the list. They will be ignored. Pro-apps-dev mailing list (Pro-apps-dev(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/pro-apps-dev/brianrg%40earthlink.net -- Darrin Cardani dcardani(a)apple.com _______________________________________________ Do not post admin requests to the list. They will be ignored. Pro-apps-dev mailing list (Pro-apps-dev(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/pro-apps-dev/pschneider%40apple.com _______________________________________________ Do not post admin requests to the list. They will be ignored. Pro-apps-dev mailing list (Pro-apps-dev(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/pro-apps-dev/site_archiver%40lists.a… If you're interested in CoreImage development, you might also check out the quartz-dev mailing list: Brian, I don't know of any examples of what you want, but it's not too difficult. I'll try to address it here. In a Core Image kernel, you pass in a sampler that samples the input image, and samplers that will sample any other images that your filter uses. So in the example I sent to the list yesterday, there were 2 samplers, one for the input image, and one for the map image: kernel vec4 Displacement (sampler image, sampler mapImage, float scale) { vec4 offset = sample (mapImage, samplerCoord (mapImage)); // <- Reads from the map image offset *= scale; return sample(image, samplerCoord(image) + offset.xy); // <- Reads from the main input image } To read a sample from a sampler, you simply call the "sample ()" function: The coordinates are a vector, and can pretty much be any real numbers. You can get the coordinate of the current pixel in any image by asking the sampler for its current coordinates using the samplerCoord () function: You can then manipulate those coordinates in any way you want. You can add to them, multiply them, use them in dot products, etc. Once you've manipulated your coordinates, then you can sample from one of the samplers. You can read more than one if you want. So a simple convolution might look like this: // Add 1 to the x coordinate vec2 rightCoord = coords + vec2 (1.0, 0.0); // Sample from the new coordinates, weight them, and add the results together, creating a very mild blur return sample (someSampler, leftCoord) * 0.25 + sample (someSampler, coords) * 0.5 + sample (someSampler, rightCoord) * 0.25; } Glad it helps! It looks to me like Displacement Distortion is using the magnitude and direction of edges in the map image to offset pixels in the source image. I believe it first converts the map image to grayscale, then finds the difference of each pixel with its neighbors in the x and y directions. It multiplies the x and y differences by the scale parameter and uses the resulting vector as an offset from the current pixel in the source image. So let's say the grayscale version of your map image looked like this: It then multiplies those values by the scale parameter. Let's say it's set to 25, so it comes up with an offset of (-3.5, 13). It adds that to the current (x,y) coordinate and samples the input image at (x - 3.5, y + 13). I wonder if you could shed some light on a specific CoreImage filter - specifically DisplacementDistortion... In Shake and in FxScript, the X-Displacement is governed by one channel in the displace image and the Y-Displacement by another. I can't find any documentation on the CI filter as to how it handles this. Patrick This email sent to brianrg(a)earthlink.net This email sent to pschneider(a)apple.com This email sent to site_archiver(a)lists.apple.com

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Re: Core Image in FxPlug example
by Darrin Cardani 29 Apr '09

29 Apr '09

site_archiver(a)lists.apple.com Delivered-To: pro-apps-dev(a)lists.apple.com vec4 aSample = sample (someSampler, someCoordinates); vec2 coords = samplerCoord (someSampler); kernel vec4 multiplyEffect(sampler someSampler) { // Get the current sampler coordinates vec2 coords = samplerCoord (someSampler); // Subtract 1 from the x coordinate vec2 leftCoord = coords - vec2 (1.0, 0.0); Let me know if that answers your question. Thanks, Darrin On Apr 29, 2009, at 1:15 AM, Brian Gardner wrote: Hi Darrin. Thank you for your examples. Very helpful. Is there any example source code for the Displacement Distortion CI filter which you mention below? Which samples 3 pixels from one image, and 1 pixel from another image? That would be very helpful for me to see. There are very few examples which use multiple (or reference) images, and take multiple samples per image. Is there any such sample code available? (Like of the Displacement Distortion filter you describe, below.) -- Brian On Apr 28, 2009, at 9:01 AM, Darrin Cardani wrote: 0.75 0.89 0.23 0.52 It takes (0.75 - 0.89) = -0.14 as the x offset It takes (0.75 - 0.23) = .52 as the y offset Does that make sense? Darrin On Apr 27, 2009, at 5:53 PM, Patrick Sheffield wrote: Thank you Darrin - this helps a lot. Thanks, -- Darrin Cardani dcardani(a)apple.com _______________________________________________ Do not post admin requests to the list. They will be ignored. Pro-apps-dev mailing list (Pro-apps-dev(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/pro-apps-dev/brianrg%40earthlink.net -- Darrin Cardani dcardani(a)apple.com _______________________________________________ Do not post admin requests to the list. They will be ignored. Pro-apps-dev mailing list (Pro-apps-dev(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/pro-apps-dev/site_archiver%40lists.a… Brian, I don't know of any examples of what you want, but it's not too difficult. I'll try to address it here. In a Core Image kernel, you pass in a sampler that samples the input image, and samplers that will sample any other images that your filter uses. So in the example I sent to the list yesterday, there were 2 samplers, one for the input image, and one for the map image: kernel vec4 Displacement (sampler image, sampler mapImage, float scale) { vec4 offset = sample (mapImage, samplerCoord (mapImage)); // <- Reads from the map image offset *= scale; return sample(image, samplerCoord(image) + offset.xy); // <- Reads from the main input image } To read a sample from a sampler, you simply call the "sample ()" function: The coordinates are a vector, and can pretty much be any real numbers. You can get the coordinate of the current pixel in any image by asking the sampler for its current coordinates using the samplerCoord () function: You can then manipulate those coordinates in any way you want. You can add to them, multiply them, use them in dot products, etc. Once you've manipulated your coordinates, then you can sample from one of the samplers. You can read more than one if you want. So a simple convolution might look like this: // Add 1 to the x coordinate vec2 rightCoord = coords + vec2 (1.0, 0.0); // Sample from the new coordinates, weight them, and add the results together, creating a very mild blur return sample (someSampler, leftCoord) * 0.25 + sample (someSampler, coords) * 0.5 + sample (someSampler, rightCoord) * 0.25; } Glad it helps! It looks to me like Displacement Distortion is using the magnitude and direction of edges in the map image to offset pixels in the source image. I believe it first converts the map image to grayscale, then finds the difference of each pixel with its neighbors in the x and y directions. It multiplies the x and y differences by the scale parameter and uses the resulting vector as an offset from the current pixel in the source image. So let's say the grayscale version of your map image looked like this: It then multiplies those values by the scale parameter. Let's say it's set to 25, so it comes up with an offset of (-3.5, 13). It adds that to the current (x,y) coordinate and samples the input image at (x - 3.5, y + 13). I wonder if you could shed some light on a specific CoreImage filter - specifically DisplacementDistortion... In Shake and in FxScript, the X-Displacement is governed by one channel in the displace image and the Y-Displacement by another. I can't find any documentation on the CI filter as to how it handles this. Patrick This email sent to brianrg(a)earthlink.net This email sent to site_archiver(a)lists.apple.com

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Re: Core Image in FxPlug example
by Brian Gardner 29 Apr '09

29 Apr '09

site_archiver(a)lists.apple.com Delivered-To: pro-apps-dev(a)lists.apple.com Domainkey-signature: a=rsa-sha1; q=dns; c=nofws; s=dk20050327; d=earthlink.net; b=OVqZr2L3/vzLbJ5znxK83UDqguCVylTkmxREYM6UBjCjrAbgnuUqWCgI4gAsDtoB; h=Received:From:To:In-Reply-To:Subject:References:Message-Id:Content-Type:Content-Transfer-Encoding:Mime-Version:Date:Cc:X-Mailer:X-ELNK-Trace:X-Originating-IP; Hi Darrin. Thank you for your examples. Very helpful. Is there any example source code for the Displacement Distortion CI filter which you mention below? Which samples 3 pixels from one image, and 1 pixel from another image? That would be very helpful for me to see. There are very few examples which use multiple (or reference) images, and take multiple samples per image. Is there any such sample code available? (Like of the Displacement Distortion filter you describe, below.) -- Brian On Apr 28, 2009, at 9:01 AM, Darrin Cardani wrote: So let's say the grayscale version of your map image looked like this: 0.75 0.89 0.23 0.52 It takes (0.75 - 0.89) = -0.14 as the x offset It takes (0.75 - 0.23) = .52 as the y offset Does that make sense? Darrin On Apr 27, 2009, at 5:53 PM, Patrick Sheffield wrote: Thank you Darrin - this helps a lot. Thanks, -- Darrin Cardani dcardani(a)apple.com _______________________________________________ Do not post admin requests to the list. They will be ignored. Pro-apps-dev mailing list (Pro-apps-dev(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/pro-apps-dev/brianrg%40earthlink.net _______________________________________________ Do not post admin requests to the list. They will be ignored. Pro-apps-dev mailing list (Pro-apps-dev(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/pro-apps-dev/site_archiver%40lists.a… Glad it helps! It looks to me like Displacement Distortion is using the magnitude and direction of edges in the map image to offset pixels in the source image. I believe it first converts the map image to grayscale, then finds the difference of each pixel with its neighbors in the x and y directions. It multiplies the x and y differences by the scale parameter and uses the resulting vector as an offset from the current pixel in the source image. It then multiplies those values by the scale parameter. Let's say it's set to 25, so it comes up with an offset of (-3.5, 13). It adds that to the current (x,y) coordinate and samples the input image at (x - 3.5, y + 13). I wonder if you could shed some light on a specific CoreImage filter - specifically DisplacementDistortion... In Shake and in FxScript, the X-Displacement is governed by one channel in the displace image and the Y-Displacement by another. I can't find any documentation on the CI filter as to how it handles this. Patrick This email sent to brianrg(a)earthlink.net This email sent to site_archiver(a)lists.apple.com

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Re: Core Image in FxPlug example
by Darrin Cardani 28 Apr '09

28 Apr '09

site_archiver(a)lists.apple.com Delivered-To: pro-apps-dev(a)lists.apple.com Darrin On Apr 28, 2009, at 12:24 PM, Darrin Cardani wrote: Darrin On Apr 28, 2009, at 12:16 PM, Darrin Cardani wrote: Darrin On Apr 28, 2009, at 9:53 AM, Patrick Sheffield wrote: I am confused, Patrick On Apr 28, 2009, at 9:01 AM, Darrin Cardani wrote: 0.75 0.89 0.23 0.52 It takes (0.75 - 0.89) = -0.14 as the x offset It takes (0.75 - 0.23) = .52 as the y offset Does that make sense? Darrin On Apr 27, 2009, at 5:53 PM, Patrick Sheffield wrote: Thank you Darrin - this helps a lot. Thanks, -- Darrin Cardani dcardani(a)apple.com -- Darrin Cardani dcardani(a)apple.com _______________________________________________ Do not post admin requests to the list. They will be ignored. Pro-apps-dev mailing list (Pro-apps-dev(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/pro-apps-dev/dcardani%40apple.com -- Darrin Cardani dcardani(a)apple.com _______________________________________________ Do not post admin requests to the list. They will be ignored. Pro-apps-dev mailing list (Pro-apps-dev(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/pro-apps-dev/dcardani%40apple.com -- Darrin Cardani dcardani(a)apple.com _______________________________________________ Do not post admin requests to the list. They will be ignored. Pro-apps-dev mailing list (Pro-apps-dev(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/pro-apps-dev/site_archiver%40lists.a… I should also mention, that it uses the red channel for x offset and the green channel for y offset. Here's a simple Core Image kernel that does a displacement. You could either put this into a QC Composition with a "Core Image Filter" object, or write an actual ImageUnit which you then load in your FxPlug: kernel vec4 Displacement (sampler image, sampler mapImage, float scale) { vec4 offset = sample (mapImage, samplerCoord (mapImage)); offset *= scale; return sample(image, samplerCoord(image) + offset.xy); } It's not too inefficient. It reads the current pixel, the next pixel to the right, and the next pixel below. It's 3 samples, which should work relatively efficiently going all the way back to the ATI 9600. Many of the filters we ship with Motion and FCP do similar things. Check out Glass Distortion, Displace, Bump Map, etc. for example. In any event, it's probably not possible to make it work the way you want as it is. It would probably be easier to write a little CoreImage filter right in Quartz Composer, and then use the QC example that was posted earlier today. I'll see if I can come up with a very simple example to help you out. So - it requires 4 pixels to determine which direction to shift each pixel? How can that work? Does it scan starting at the upper left and take the pixel and its right most and then the two pixels below it to determine where to move the first pixel? and how could I even build such a buffer, since the value that was subtracted to determine the first pixel's displacement is being subtracted FROM to determine the second pixel. And what happens at the right/ bottom edges? Seems FRIGHTFULLY inefficient... why not use the RGBA values for this? Glad it helps! It looks to me like Displacement Distortion is using the magnitude and direction of edges in the map image to offset pixels in the source image. I believe it first converts the map image to grayscale, then finds the difference of each pixel with its neighbors in the x and y directions. It multiplies the x and y differences by the scale parameter and uses the resulting vector as an offset from the current pixel in the source image. So let's say the grayscale version of your map image looked like this: It then multiplies those values by the scale parameter. Let's say it's set to 25, so it comes up with an offset of (-3.5, 13). It adds that to the current (x,y) coordinate and samples the input image at (x - 3.5, y + 13). I wonder if you could shed some light on a specific CoreImage filter - specifically DisplacementDistortion... In Shake and in FxScript, the X-Displacement is governed by one channel in the displace image and the Y-Displacement by another. I can't find any documentation on the CI filter as to how it handles this. Patrick This email sent to dcardani(a)apple.com This email sent to dcardani(a)apple.com This email sent to site_archiver(a)lists.apple.com

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Re: Core Image in FxPlug example
by Darrin Cardani 28 Apr '09

28 Apr '09

site_archiver(a)lists.apple.com Delivered-To: pro-apps-dev(a)lists.apple.com kernel vec4 Displacement (sampler image, sampler mapImage, float scale) { vec4 offset = sample (mapImage, samplerCoord (mapImage)); offset *= scale; return sample(image, samplerCoord(image) + offset.xy); } Darrin On Apr 28, 2009, at 12:16 PM, Darrin Cardani wrote: Darrin On Apr 28, 2009, at 9:53 AM, Patrick Sheffield wrote: I am confused, Patrick On Apr 28, 2009, at 9:01 AM, Darrin Cardani wrote: 0.75 0.89 0.23 0.52 It takes (0.75 - 0.89) = -0.14 as the x offset It takes (0.75 - 0.23) = .52 as the y offset Does that make sense? Darrin On Apr 27, 2009, at 5:53 PM, Patrick Sheffield wrote: Thank you Darrin - this helps a lot. Thanks, -- Darrin Cardani dcardani(a)apple.com -- Darrin Cardani dcardani(a)apple.com _______________________________________________ Do not post admin requests to the list. They will be ignored. Pro-apps-dev mailing list (Pro-apps-dev(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/pro-apps-dev/dcardani%40apple.com -- Darrin Cardani dcardani(a)apple.com _______________________________________________ Do not post admin requests to the list. They will be ignored. Pro-apps-dev mailing list (Pro-apps-dev(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/pro-apps-dev/site_archiver%40lists.a… Here's a simple Core Image kernel that does a displacement. You could either put this into a QC Composition with a "Core Image Filter" object, or write an actual ImageUnit which you then load in your FxPlug: It's not too inefficient. It reads the current pixel, the next pixel to the right, and the next pixel below. It's 3 samples, which should work relatively efficiently going all the way back to the ATI 9600. Many of the filters we ship with Motion and FCP do similar things. Check out Glass Distortion, Displace, Bump Map, etc. for example. In any event, it's probably not possible to make it work the way you want as it is. It would probably be easier to write a little CoreImage filter right in Quartz Composer, and then use the QC example that was posted earlier today. I'll see if I can come up with a very simple example to help you out. So - it requires 4 pixels to determine which direction to shift each pixel? How can that work? Does it scan starting at the upper left and take the pixel and its right most and then the two pixels below it to determine where to move the first pixel? and how could I even build such a buffer, since the value that was subtracted to determine the first pixel's displacement is being subtracted FROM to determine the second pixel. And what happens at the right/bottom edges? Seems FRIGHTFULLY inefficient... why not use the RGBA values for this? Glad it helps! It looks to me like Displacement Distortion is using the magnitude and direction of edges in the map image to offset pixels in the source image. I believe it first converts the map image to grayscale, then finds the difference of each pixel with its neighbors in the x and y directions. It multiplies the x and y differences by the scale parameter and uses the resulting vector as an offset from the current pixel in the source image. So let's say the grayscale version of your map image looked like this: It then multiplies those values by the scale parameter. Let's say it's set to 25, so it comes up with an offset of (-3.5, 13). It adds that to the current (x,y) coordinate and samples the input image at (x - 3.5, y + 13). I wonder if you could shed some light on a specific CoreImage filter - specifically DisplacementDistortion... In Shake and in FxScript, the X-Displacement is governed by one channel in the displace image and the Y-Displacement by another. I can't find any documentation on the CI filter as to how it handles this. Patrick This email sent to dcardani(a)apple.com This email sent to site_archiver(a)lists.apple.com

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Re: Core Image in FxPlug example
by Darrin Cardani 28 Apr '09

28 Apr '09

site_archiver(a)lists.apple.com Delivered-To: pro-apps-dev(a)lists.apple.com Darrin On Apr 28, 2009, at 9:53 AM, Patrick Sheffield wrote: Seems FRIGHTFULLY inefficient... why not use the RGBA values for this? I am confused, Patrick On Apr 28, 2009, at 9:01 AM, Darrin Cardani wrote: 0.75 0.89 0.23 0.52 It takes (0.75 - 0.89) = -0.14 as the x offset It takes (0.75 - 0.23) = .52 as the y offset Does that make sense? Darrin On Apr 27, 2009, at 5:53 PM, Patrick Sheffield wrote: Thank you Darrin - this helps a lot. Thanks, -- Darrin Cardani dcardani(a)apple.com -- Darrin Cardani dcardani(a)apple.com _______________________________________________ Do not post admin requests to the list. They will be ignored. Pro-apps-dev mailing list (Pro-apps-dev(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/pro-apps-dev/site_archiver%40lists.a… It's not too inefficient. It reads the current pixel, the next pixel to the right, and the next pixel below. It's 3 samples, which should work relatively efficiently going all the way back to the ATI 9600. Many of the filters we ship with Motion and FCP do similar things. Check out Glass Distortion, Displace, Bump Map, etc. for example. In any event, it's probably not possible to make it work the way you want as it is. It would probably be easier to write a little CoreImage filter right in Quartz Composer, and then use the QC example that was posted earlier today. I'll see if I can come up with a very simple example to help you out. So - it requires 4 pixels to determine which direction to shift each pixel? How can that work? Does it scan starting at the upper left and take the pixel and its right most and then the two pixels below it to determine where to move the first pixel? and how could I even build such a buffer, since the value that was subtracted to determine the first pixel's displacement is being subtracted FROM to determine the second pixel. And what happens at the right/bottom edges? Glad it helps! It looks to me like Displacement Distortion is using the magnitude and direction of edges in the map image to offset pixels in the source image. I believe it first converts the map image to grayscale, then finds the difference of each pixel with its neighbors in the x and y directions. It multiplies the x and y differences by the scale parameter and uses the resulting vector as an offset from the current pixel in the source image. So let's say the grayscale version of your map image looked like this: It then multiplies those values by the scale parameter. Let's say it's set to 25, so it comes up with an offset of (-3.5, 13). It adds that to the current (x,y) coordinate and samples the input image at (x - 3.5, y + 13). I wonder if you could shed some light on a specific CoreImage filter - specifically DisplacementDistortion... In Shake and in FxScript, the X-Displacement is governed by one channel in the displace image and the Y-Displacement by another. I can't find any documentation on the CI filter as to how it handles this. Patrick This email sent to site_archiver(a)lists.apple.com

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Re: Core Image in FxPlug example
by Patrick Sheffield 28 Apr '09

28 Apr '09

site_archiver(a)lists.apple.com Delivered-To: pro-apps-dev(a)lists.apple.com Domainkey-signature: a=rsa-sha1; q=dns; c=nofws; s=dk20050327; d=earthlink.net; b=VTQnbjY9QdL/gZzX2sjdHbN3XJ4M1pG7GcZWiBJXyGtncn/MNJAY8wUeDC8kFl7f; h=Received:Cc:Message-Id:From:To:In-Reply-To:Content-Type:Mime-Version:Subject:Date:References:X-Mailer:X-ELNK-Trace:X-Originating-IP; Seems FRIGHTFULLY inefficient... why not use the RGBA values for this? I am confused, Patrick On Apr 28, 2009, at 9:01 AM, Darrin Cardani wrote: So let's say the grayscale version of your map image looked like this: 0.75 0.89 0.23 0.52 It takes (0.75 - 0.89) = -0.14 as the x offset It takes (0.75 - 0.23) = .52 as the y offset Does that make sense? Darrin On Apr 27, 2009, at 5:53 PM, Patrick Sheffield wrote: Thank you Darrin - this helps a lot. Thanks, -- Darrin Cardani dcardani(a)apple.com _______________________________________________ Do not post admin requests to the list. They will be ignored. Pro-apps-dev mailing list (Pro-apps-dev(a)lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/pro-apps-dev/site_archiver%40lists.a… This email sent to site_archiver(a)lists.apple.com So - it requires 4 pixels to determine which direction to shift each pixel? How can that work? Does it scan starting at the upper left and take the pixel and its right most and then the two pixels below it to determine where to move the first pixel? and how could I even build such a buffer, since the value that was subtracted to determine the first pixel's displacement is being subtracted FROM to determine the second pixel. And what happens at the right/bottom edges? Glad it helps! It looks to me like Displacement Distortion is using the magnitude and direction of edges in the map image to offset pixels in the source image. I believe it first converts the map image to grayscale, then finds the difference of each pixel with its neighbors in the x and y directions. It multiplies the x and y differences by the scale parameter and uses the resulting vector as an offset from the current pixel in the source image. It then multiplies those values by the scale parameter. Let's say it's set to 25, so it comes up with an offset of (-3.5, 13). It adds that to the current (x,y) coordinate and samples the input image at (x - 3.5, y + 13). I wonder if you could shed some light on a specific CoreImage filter - specifically DisplacementDistortion... In Shake and in FxScript, the X-Displacement is governed by one channel in the displace image and the Y-Displacement by another. I can't find any documentation on the CI filter as to how it handles this. Patrick smime.p7s

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