What does OziExplorer mean by "RGB value"?

1
votes

The OziExplorer File Formats documentation describes it's foreground and background colour fields as "RGB values". I have tried for about an hour to work out what it means by that. For example, here are some colours as exported by OziExplorer:

  • Red: 5450740
  • Green: 65280
  • Blue: 16711680
  • Grey: 12632256
  • White: 16777215
  • "Transparent": 13158342

I can't be 100% sure, but by the looks of it, the red, green and blue colours are completely red, green and blue, meaning #FF0000 etc.

What I'm trying to do is understand what the above numbers mean. What is the link between the colour (255, 0, 0) and the number 5450740? Where does the transparency come in? Can somebody help me clear this up?

I did notice a couple of interesting things. The hex value #FF0000 has the decimal value 16711680, which is the value Ozi Explorer output for blue. One would think #FF0000 would mean red. Additionally, white (16777215) has the hex value #FFFFFF, which is at least "correct" according to the #RRGGBB standard.

Edit: After trying to create a waypoint file with the decimal values of #FF0000, #00FF00 and #0000FF (red, green and blue) I found out that OziExplorer does indeed swap red and green. I still have no clue why it does that though, and I have no idea where the transparency fits in to this.

1
colorsrgb
Off-the-wall hypothesis: The wikipedia Talk page for the BMP file format article suggests that there's a "normal non-bitfield" variation on the format that stores the color bytes as GRB instead of RGB. Could it be using this BMP variation internally? At the bottom of the page there's alos a diagram of the bitfield format in question... - Charles

1 Answers

0
votes

Well it seems that the colours are just normal 24-bit RGB values, but mirrored. Red is #0000FF, green is #00FF00 as usual and blue is #FF0000. Also it turns out that there is no "alpha channel", just the colour value #C6C7C8 which means "transparent".