Data commit

Task/Bitmap-Histogram/BBC-BASIC/bitmap-histogram.basic

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+      INSTALL @lib$+"SORTLIB"
+      Sort% = FN_sortinit(0,0)
+
+      Width% = 200
+      Height% = 200
+
+      VDU 23,22,Width%;Height%;8,16,16,128
+      *display c:\lenagrey
+
+      DIM hist%(255), idx%(255)
+      FOR i% = 0 TO 255 : idx%(i%) = i% : NEXT
+
+      REM Build histogram:
+      FOR y% = 0 TO Height%-1
+        FOR x% = 0 TO Width%-1
+          l% = FNgetpixel(x%,y%) AND &FF
+          hist%(l%) += 1
+        NEXT
+      NEXT y%
+
+      REM Sort histogram:
+      C% = 256
+      CALL Sort%, hist%(0), idx%(0)
+
+      REM Find median:
+      total% = SUM(hist%())
+      half% = 0
+      FOR i% = 0 TO 255
+        half% += hist%(i%)
+        IF half% >= total%/2 THEN
+          median% = idx%(i%)
+          EXIT FOR
+        ENDIF
+      NEXT
+
+      REM Display black & white version:
+      FOR y% = 0 TO Height%-1
+        FOR x% = 0 TO Width%-1
+          l% = FNgetpixel(x%,y%) AND &FF
+          IF l% > median% THEN
+            PROCsetpixel(x%,y%,255,255,255)
+          ELSE
+            PROCsetpixel(x%,y%,0,0,0)
+          ENDIF
+        NEXT
+      NEXT y%
+      END
+
+      DEF PROCsetpixel(x%,y%,r%,g%,b%)
+      COLOUR 1,r%,g%,b%
+      GCOL 1
+      LINE x%*2,y%*2,x%*2,y%*2
+      ENDPROC
+
+      DEF FNgetpixel(x%,y%)
+      LOCAL col%
+      col% = TINT(x%*2,y%*2)
+      SWAP ?^col%,?(^col%+2)
+      = col%