90 degree rotation algorithm.

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2 total messages Started by Sim Zacks Mon, 07 Dec 1998 00:00

#78

Author: Sim Zacks
Date: Mon, 07 Dec 1998 00:00

19 lines
1361 bytes

Could you please look at the algorithm I just figured out and tell me
what you think of it.
If there's a better method, or anything, please let me know.
I am dealing with 1 bit per pixel images.

90 degree rotation

1. Imagewidth := pixels per row
2. Imageheight := pixels per column
3. Newrownumber := imageheight � rownum +1
4. Firstpixelinrow := imagewidth * (rownumber-1) +1
5. Pixelnuminrow := pixelnum � first pixel in row
6. Newpixelnum := pixelnuminrow * imageheight+newrownumber;
7. CorrectByte := newpixelnum div 8 + 1;
8. Allocate enough memory for new image
9. Fill the memory with 0�s
10. AND the current byte to get the current pixel
11. OR the current Pixel with the Byte you want to put it into
12. Do this for entire image.

Re: 90 degree rotation algorithm.

#79

Author: Sim Zacks
Date: Mon, 07 Dec 1998 00:00

24 lines
1524 bytes

I screwed up in calculating the new pixel number.
Can anyone help?

Sim Zacks wrote:

> Could you please look at the algorithm I just figured out and tell me
> what you think of it.
> If there's a better method, or anything, please let me know.
> I am dealing with 1 bit per pixel images.
>
> 90 degree rotation
>
> 1. Imagewidth := pixels per row
> 2. Imageheight := pixels per column
> 3. Newrownumber := imageheight � rownum +1
> 4. Firstpixelinrow := imagewidth * (rownumber-1) +1
> 5. Pixelnuminrow := pixelnum � first pixel in row
> 6. Newpixelnum := pixelnuminrow * imageheight+newrownumber;
> 7. CorrectByte := newpixelnum div 8 + 1;
> 8. Allocate enough memory for new image
> 9. Fill the memory with 0�s
> 10. AND the current byte to get the current pixel
> 11. OR the current Pixel with the Byte you want to put it into
> 12. Do this for entire image.

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