| blob | 045d959a85abc2d4913013f9ef6c35bfd65d6fed |
1 The _big.png images are the ones to use for editing.
3 The _small.ilbm images are the ones to be used in Locale prefs program and
4 therefore scaled down to a smaller size.
6 +--------------------------------------------------------------------------+
7 | |
8 | How to correctly create the small images out of the big images with GIMP |
9 | |
10 +--------------------------------------------------------------------------+
12 earthmap:
13 =========
15 This image is black&white in indexed format. Before scaling down the image
16 convert it to RGB format:
18 GIMP: Image -> Mode -> RGB
20 The reason for this is, that then the scaled image will be sort of anti-
21 aliased (filtered down). Now to scale the image down:
23 GIMP: Image -> Scale Image: New Width = 416, Height = 240
25 Now convert the image back to indexed format:
27 GIMP: Image -> Mode -> Indexed
29 In the "Indexed Color Conversion" requester activate
30 "Generate Optimal Palette" and "No color Dithering".
31 Set the "# of Colors" to something < 128!!! 32 should
32 be enough.
34 For some strange reason, GIMP might have created an indexed
35 palette, which does not contain any "full black" (#000000)
36 and "full white" (#FFFFFF) colors anymore. Although most of
37 the pixels in the image were in this colors before conversion.
38 So to fix this normalize the palette:
40 GIMP: Image -> Colors -> Auto -> Normalize
42 Now if you have the GIMP ilbm plugin you can save the image as
43 "earthmap_small.ilbm". If not save it in some other indexed
44 format (GIF/PNG) and then use some tool to convert it to IFF
45 ILBM.
48 timezones:
49 ==========
51 This image is also in indexed format. But anyway this time we
52 do *not* convert it to RGB for scaling down. Instead directly
53 scale down:
55 GIMP: Image -> Scale Image: New Width = 416, Height = 240
57 Now if you have the GIMP ilbm plugin you can save the image as
58 "timezones_small.ilbm". If not save it in some other indexed
59 format (GIF/PNG) and then use some tool to convert it to IFF
60 ILBM.
62 +--------------------------------------------------------------------------+
63 | |
64 | Editing earthmap_big.png |
65 | |
66 +--------------------------------------------------------------------------+
68 Load earthmap_big.png and directly edit it. Do *not* change palette. The
69 colors for the ocean and the continents can be directly adjusted in Locale
70 prefs program source, because earthmap image is basically treated as 8 bit
71 alpha mask = ~ intensity values of ocean. The smaller (= darker) the in-
72 tensity the bigger the continent color will show through. So completely
73 black (#000000) areas will be in continent color. And completely white
74 (#FFFFFF) areas will be in ocean color. The color values in between (which
75 are generated during scale down process -> anti aliasing) will be some mix
76 between ocean color and continent color (-> alpha blending).
78 +--------------------------------------------------------------------------+
79 | |
80 | Editing timezones_big.png |
81 | |
82 +--------------------------------------------------------------------------+
84 To edit timezones_big.png load it and convert it to RGB format:
86 GIMP: Image -> Mode -> RGB
88 Remember *not* to save it back to disk in RGB format! Before saving convert
89 it back to indexed format:
91 GIMP: Image -> Mode -> Indexed
93 In the "Indexed Color Conversion" requester activate
94 "Generate Optimal Palette" and "No color Dithering".
95 Set the "# of Colors" to 64.
97 Each timezone is painted in a different color. The color (RGB value) is very
98 important, because the timezone number is "encoded" into the upper two bits
99 (bits 6 and 7) of each color gun (red/green/blue). Each color gun has 8 bits
100 so there are an overall of 24 bit (we ignore alpha):
102 R7 R6 R5 R4 R3 R2 R1 R0 G7 G6 G5 G4 G3 G2 G1 G0 B7 B6 B5 B4 B3 B2 B1 B0
104 Now taking the upper two bits of each color gun:
106 R7 R6 G7 G6 B7 B6
108 We get the "id" of the timezone.
110 Timezones:
111 ==========
113 +----+------+----------------------+
114 | ID | NAME | Time offset from GMT |
115 +----+------+----------------------+
116 | 0 | Z | 0:00 |
117 | 1 | A | + 1:00 |
118 | 2 | B | + 2:00 |
119 | 3 | C | + 3:00 |
120 | 4 | C* | + 3:30 |
121 | 5 | D | + 4:00 |
122 | 6 | D* | + 4:30 |
123 | 7 | E | + 5:00 |
124 | 8 | E* | + 5:30 |
125 | 9 | F | + 6:00 |
126 | 10 | F* | + 6:30 |
127 | 11 | G | + 7:00 |
128 | 12 | H | + 8:00 |
129 | 13 | I | + 9:00 |
130 | 14 | I* | + 9:30 |
131 | 15 | K | + 10:00 |
132 | 16 | K* | + 10:30 |
133 | 17 | L | + 11:00 |
134 | 18 | L* | + 11:30 |
135 | 19 | M | + 12:00 |
136 | 20 | M* | + 13:00 |
137 | 21 | N | - 1:00 |
138 | 22 | O | - 2:00 |
139 | 23 | P | - 3:00 |
140 | 24 | P* | - 3:30 |
141 | 25 | Q | - 4:00 |
142 | 26 | R | - 5:00 |
143 | 27 | S | - 6:00 |
144 | 28 | T | - 7:00 |
145 | 29 | U | - 8:00 |
146 | 30 | U* | - 8:30 |
147 | 31 | V | - 9:00 |
148 | 32 | V* | - 9:30 |
149 | 33 | W | - 10:00 |
150 | 34 | X | - 11:00 |
151 | 35 | Y | - 12:00 |
152 +----+------+----------------------+
154 I want to know the RGB value in which to paint the timezone area with ID <id>:
156 ((<id> & 0x30) / 16) * 0x400000 +
157 ((<id> & 0x0C) / 4) * 0x4000 +
158 ( <id> & 0x03 ) * 0x40
160 I see this area painted in RGB <rgb> and want to know the timezone area ID of it:
162 ((<rgb> & 0xC00000) / 0x400000) * 16 +
163 ((<rgb> & 0x00C000) / 0x4000) * 4 +
164 ((<rgb> & 0x0000C0) / 0x40)
166 ----------------------------------------------------------------------------
167 Georg Steger <georg.steger@rolmail.net>