Questions and postings pertaining to the usage of ImageMagick regardless of the interface. This includes the command-line utilities, as well as the C and C++ APIs. Usage questions are like "How do I use ImageMagick to create drop shadows?".
You should not use a size with height = 0 (-size 500x0). That is not good. Is that a typo mistake?
What is your ImageMagick version and platform? Please always provide that as syntax may vary. I assume from your command, though not properly printed, is Windows.
I do not understand the question? Please post an example input and output of what you want. Where do you want the radial gradient.
I am not sure if I understand, but here is what I think you might want. If I assume you want the output to be 200x118. Then I resize your image to 84x84. Pad to 200x84. Then create the linear gradient mirror effect with a 200x34 bottom part. Append the two. Then composite that over a radial gradient.
If this is not what you want, then please be more specific or show an example of the result you want.
When i change radial-gradient: by radial-gradient:white-LightGray i have a linear gradient.
But if I change by radial-gradient:red-blue i have a radial-gradient
the first argument in your command, whichwas white, will replace black, so you would be getting a white and light gray gradient. It is still radial, but may not look very much so.