Масштабирования растровых рисунков Опции

[Bokul]

Подскажите, пожалуйста, алгоритм масштабирования рисунков. Рисунок представляет собой двумерный массив, каждый елемент которого определяет цвет соответствующего пикселя на рисунке.

Сообщение отредактировано: Bokul - 22.08.2006 9:46

[Archon]

Вот, что я нашёл в обучалках асфиксии. На аглицком наречии, но всё же довольно неплохо написано.

For the horizontal area, I am going to calculate a certain step value. I
will then trace along the bitmap, adding this step to my position, and
placing the nearest pixel on to the screen. Let me explain this simpler ...

Let us say I have a 10 pixel wide bitmap. I want to squish it into 5 pixels.
Along the bitmap, I would draw every second pixel to screen. In ascii :

1234567890 13579
+--------+ +---+
| | | |
| bitmap | | |dest
| | | |
+--------+ +---+

As you can see, by stepping through every second pixel, I have shrunk the
bitmap to a width of 5 pixels.

The equation is as follows :

step = origionalwidth / wantedwidth;

Let us say we have a 100 pixel wide bitmap, which we want to get to 20 pixels.

step = 100 / 20
step = 5

If we draw every fifth pixel from the origional bitmap, we have scaled it down
correctly! This also works for all values, if step is of type real.

We also find the step for the height in the same way.

Our horizontal loop is as follows :

For loop1:=1 to wantedwidth do BEGIN
putpixel (loop1,height,bitmap[round (curpos)],vga);
curpos:=curpos+xstep;
END;

And the vertical loop is much the same. Easy huh?