XPost: misc.phone.mobile.iphone, alt.comp.os.windows-10   
   From: mariasophia@comprehension.com   
      
   Maria Sophia wrote:   
   >  C:\> gvim wallpaper.ppm   
   >       P3 400 100 255 171 205 239   
   >  C:\> magick wallpaper.ppm wallpaper.png   
   > That creates a 400x100 pixel solid #ABCDEF PNG, identical to the   
   > downloaded image created from the single-color-image web site above.   
      
   Oops. I wrote that PSA off the cuff in a few minutes so I didn't realize   
   there was missing data in the description that was actually in my ppm file.   
     C:\> type wallpaper.ppm   
          P3 1 1 255 171 205 239   
     C:\> magick wallpaper.ppm wallpaper.png   
      
   That was my mistake. The prior PPM header declares 400x100 pixels   
   (40,000 pixels total), but only provides one pixel's worth of RGB   
   data. ImageMagick is stricter than Irfanview about PPM completeness.   
      
   The PPM I actually used when testing was:   
      P3 1 1 255 171 205 239   
   which is a complete 1x1 PPM. ImageMagick accepts that file because   
   it contains exactly the amount of pixel data the header declares.   
      
   P3  -> Magic number. Means "ASCII PPM" (Portable Pixmap, text format).   
   1   -> Image width in pixels. This file contains exactly 1 column.   
   1   -> Image height in pixels. This file contains exactly 1 row.   
   255 -> Maximum channel value. Defines the scale for R, G, B.   
          255 means each color channel ranges from 0 to 255.   
   171 -> Red channel value for the single pixel (0-255).   
          This corresponds to hex AB.   
   205 -> Green channel value for the single pixel (0-255).   
          This corresponds to hex CD.   
   239 -> Blue channel value for the single pixel (0-255).   
          This corresponds to hex EF.   
      
   IrfanView is more forgiving than ImageMagick. If a PPM ends early,   
   IrfanView simply repeats the last pixel to fill the image. That is   
   why my original example appeared to work in IrfanView but not in   
   ImageMagick and I accidentally didn't make that distinction prior.   
      
   Mea culpa!   
      
   The correct minimal PPM for a solid color is therefore:   
      P3 1 1 255 R G B   
   Then you can scale it to any size you want using any way you want.   
      
   For example:   
    C:\> magick wallpaper.ppm -scale 400x100! wallpaper.png   
      
    -scale -> Resize operation.   
              Tells ImageMagick to scale the image to a new size.   
    400x100! -> Target dimensions for the resize.   
                400 = width in pixels   
                100 = height in pixels   
                ! = force exact size, ignore aspect ratio.   
                (The bang means to stretch or squash if needed.)   
      
   This produces a mathematically perfect solid-color image of any   
   desired resolution such as these for my three platforms I own:   
      
   a. Windows (1920x1080)   
      C:\> magick wallpaper.ppm -scale 1920x1080! win-1920x1080.png   
      
   b. Android (Galaxy A32-5G, 1600x720)   
      C:\> magick wallpaper.ppm -scale 1600x720! android-1600x720.png   
      
   c. iOS (10th-gen iPad, 2360x1640)   
      C:\> magick wallpaper.ppm -scale 2360x1640! ipad-2360x1640.png   
      
   As always, these PSAs and Tutorials are written to help everyone.   
   If/when you find an error, please improve so that everyone benefits.   
   --   
   If we think we understand something, we don't. But if we think we don't   
   quite yet understand something, then we're just beginning to understand it.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)