Brajas When used with the identify utility, use this option to print information about the image in a format of your choosing. The shorter forms are scaled up, if necessary by replication. This option can account for these differences. Only the text antiaalias is affected by the —gravity option. Use Ellipse to draw a partial ellipse centered at the given point with the x-axis and y-axis radius and start and end of arc in degrees e. ImageMagick If the -mosaic option appears after all of the input images, all images are included in the mosaic.
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Anti-Aliasing Introduction ImageMagick when it draws images, does so in a very particular way. It draws them with a operation call "anti-aliasing". But as you can see when the image is magnified it has a whole range of colors. This is a fancy term that means it fills in edge pixels of the object with a mix of colors and even transparencies, to make the object look smoother.
But the result is not very nice at all. On the latest IM a single line of pixels is drawn, in a staircase like manner. Basically this is not something you would normally want to do.
But if you want specific colors, then you will need to accept this, or use other techniques such as color quantization to ensure you only use certain colors. Note that there are actually two forms of anti-aliasing happening. The first is a blending of the white and black colors in the image, producing various color shades, grey in this case. The other form is a blending of the color and transparency to generate semi-transparent pixels in the image.
The later is something you will need to keep in mind, as many image formats, such as GIF , can not handle semi-transparent pixels, and will either make such pixels fully-opaque or or fully-transparent. The examples on GIF Boolean Transparency demonstrate methods by which you can control the handling of semi-transparent pixels wehn saving to such formats.
Summary Anti-Aliasing is very important in any sort of image drawing, and something you should keep in mind. Without consideration of the mixed colors and semi-transparent pixels generated by IM anti-aliasing, your own image creations can come out looking very bad in some formats.
This becomes even more important when you are creating images in an image format which does not allow semi-transparent pixels, such as the wide spread "GIF" format.
I have been told that this will be the focus of a later release of IM. Under Construction Better ways of drawing without anti-aliasing, to generate images with exact colors. Specifically, draw into a transparent canvas, threshold the alpha channel, then overlay, so only fully-opaque pixels are ever drawn. Unfortunatally this is not available in ImageMagick, and may never be as it is not needed in a fully anti-aliased drawing environment.
For example the normal IM way of drawing a circle produces a lot of grey anti-aliasing colors to give the circle a smooth appearance. But you can also make the stroke width too small, especially with odd sized radii. Especally a circle that is slightly off center. There is no ideal solution for all situations For example this circle which is not centered on a pixel, or a pixel boundary, not only has gaps at the top, but is also too thick at the bottom!
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Anti-Aliasing Introduction ImageMagick when it draws images, does so in a very particular way. It draws them with a operation call "anti-aliasing". But as you can see when the image is magnified it has a whole range of colors. This is a fancy term that means it fills in edge pixels of the object with a mix of colors and even transparencies, to make the object look smoother. But the result is not very nice at all.