Legacy ImageMagick Discussions Archive

I have tested with the latest version, ImageMagick 6.8.9-8, and everything works correctly. But with version 6.7.7.X, it always throws this error, "QueueAuthenticPixels: Assertion `id < (int) cache_info->number_threads' failed.", if I allow more than 4 threads. Anyway, if you are having this issue ...

Hi, I know MinGW is not the focus of ImageMagick, but hopefully I have a very simple question to answer. When running ./configure on the latest version of ImageMagick in MinGW on Windows 7, I was curious about the following snippet (from the ./configure script): if test "${GDI32_LIBS}x" != 'x'; then ...

How goes the implementation of OpenMP 4.0 with your Intel Phi processor? Any results to share with the community yet? As I've mentioned before, if you need any help, I would be happy to assist or even possibly donate money to help with this feature. I think it will be a tremendous capability for ...

I finally figured out the C++ API version of these commands, and I also understood why you negated the extracted (i.e. grayscale) alpha channel before multiplying the mask's grayscale. For those who are interested, here is my working C++ code to apply a transparency mask to an image that already ...

Thanks for the quick reply! You rock! Let me take a look at your command line version, and see if I can figure out how to reproduce the steps with the C++ API. On first look, the only think I am unclear on is why you are negating the mask?

Hi fmw42! Thanks for the example, that makes perfect sense. However, I realized that my example was flawed and did not reveal my true issue. My primary issue is preserving the alpha channel in the layer that the mask is applied to. So, here is an example that correctly demonstrates what I am trying ...

Here are a few test images that demonstrates what should happen. 1) The grayscale mask I need to apply to the 'front' image http://openshot.org/files/mask.png 2) The 'front' image, which needs the mask applied http://openshot.org/files/front.png 3) The background image, which already contains an ...

Yes, there is a PlusCompositeOp ... but just like the MultiplyCompositeOp operator, it does not seem to work (or do anything) for me. I will also try these commands on a newer version of ImageMagick, as my current one is a few versions old. However, if anyone here knows how to do the above command ...

Hi fmw42, I gave your approach a try, to the best of my understanding (using the C++ API). However, when trying to use the MultiplyCompositeOp composite operator, it does not produce a noticeable effect. In other words, it does not seem like the alpha channels are combining. In fact, i don't see any ...

Thanks for the suggestion fmw42. I'm not sure the equivalent C++ way to do those things. However, i did find a manual way to add the opacity values of 2 images in the C++ API. Warning, it is slow and I'm sure there is a better way. =) // Add 2 alpha channels together (i.e. maintain the original ...

I'm just thinking out loud, but it seems like there might be a need for another composite operator, called AddOpacityCompositeOp, which adds the opacity values together and prevents any overflows. This would be very useful when trying to combine alpha channels together. =)

Hi! I am trying to combine multiple alpha channels together in C++, and am having trouble figuring out the best approach. For example, I have an image with an existing alpha channel, and I want to apply a grayscale mask to it, modifying its alpha channel (but not completely replacing it). I've tried ...

Thanks for the response. I will install the newest version of ImageMagick (6.8.6-9) and let you know if I have the same issues.

Greetings! When I recently updated ImageMagick to version 6.7.7-10, it started giving me an assertion failure related to the number of threads. My program uses OpenMP as well, so I imagine this is related to that fact. But previous versions of ImageMagick worked fine with no assertion failures. Now ...

Thanks for the update! Let me know if I can be of any assistance.