1. Lightning-Fast Bitmap Cropping
I'm coding like hell right now, and I had to come up with a way to crop (ie.
clip) a standard Euphoria bitmap.
I wrote a routine that I think is lightning-fast.
I has only being tested on a 640*22 bitmap, so maybe it's slow on larger
bitmaps (???).
If you don't know what cropping is, it's cutting out a rectangular area from
a bitmap, and saving that area.
You can use this to perform clipping aswell.
Here it is, try it out with Euphoria 2.0+, and tell me if it explodes your
keyboard;
global function crop_image(sequence bmp,sequence rect)
sequence ret
integer y
ret = repeat(repeat(0,rect[3]-rect[1]),rect[4]-rect[2])
y = 1
for i = rect[2] to rect[4]-1 do -- To the height of the cropping rect
ret[y][1..rect[3]-rect[1]] = bmp[2][i][rect[1]..rect[3]-1]
y = y + 1
end for
return ret
end function
Mike The Spike
PS. Use
Back to code-code-code!!
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2. Re: Lightning-Fast Bitmap Cropping
Elementary lesson in Euphoria optimization, almost entirely dedicated
to you, Mike the Spike...
yours:
global function crop_image(sequence bmp,sequence rect)
sequence ret
integer y
ret = repeat(repeat(0,rect[3]-rect[1]),rect[4]-rect[2])
y = 1
for i = rect[2] to rect[4]-1 do -- To the height of the cropping rect
ret[y][1..rect[3]-rect[1]] = bmp[2][i][rect[1]..rect[3]-1]
y = y + 1
end for
return ret
end function
mine:
global function crop(sequence bmp,integer x,integer y,integer
w,integer h)
sequence s
integer x2
s = repeat(repeat(0,w),h)
x2 = x+w-1
for i = 1 to h do
s[i] = bmp[y][x..x2]
y += 1
end for
return s
end function
Much prettier, eh, pal?! Much faster too! I grabbed the first bitmap
I spotted on my drive, a 320x200x256 pic, ran it through 1000
iterations, removing a 20 pixel border from it, just for the heck of
it. Your "Lightning-Fast", routine took 6.63 seconds, my plain effort
just 3.49 seconds. I did not bother with any more tests, it's just not
worth it. I hope even you can appreciate the difference. jiri
Btw, your routine cheats: it does not show both the last column and
the last row of pixels of the cropped image.;)
3. Re: Lightning-Fast Bitmap Cropping
>Elementary lesson in Euphoria optimization, almost entirely dedicated
>to you, Mike the Spike...
>
>
>yours:
>
>global function crop_image(sequence bmp,sequence rect)
>sequence ret
>integer y
>ret = repeat(repeat(0,rect[3]-rect[1]),rect[4]-rect[2])
>y = 1
>
>for i = rect[2] to rect[4]-1 do -- To the height of the cropping rect
> ret[y][1..rect[3]-rect[1]] = bmp[2][i][rect[1]..rect[3]-1]
> y = y + 1
>end for
>return ret
>end function
>
>
>mine:
>
>global function crop(sequence bmp,integer x,integer y,integer
>w,integer h)
> sequence s
> integer x2
> s = repeat(repeat(0,w),h)
> x2 = x+w-1
> for i = 1 to h do
> s[i] = bmp[y][x..x2]
> y += 1
> end for
> return s
>end function
>
>Much prettier, eh, pal?! Much faster too! I grabbed the first bitmap
>I spotted on my drive, a 320x200x256 pic, ran it through 1000
>iterations, removing a 20 pixel border from it, just for the heck of
>it. Your "Lightning-Fast", routine took 6.63 seconds, my plain effort
>just 3.49 seconds. I did not bother with any more tests, it's just not
>worth it. I hope even you can appreciate the difference. jiri
>
>Btw, your routine cheats: it does not show both the last column and
>the last row of pixels of the cropped image.;)
Thanks pal!
I knew there was a faster way, I was just too lazy to find out wich one it
was :p
Now I don't have to anymore, thanks again!
Mike The Spike
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4. Re: Lightning-Fast Bitmap Cropping
>Elementary lesson in Euphoria optimization, almost entirely dedicated
>to you, Mike the Spike...
>
>
>yours:
>
>global function crop_image(sequence bmp,sequence rect)
>sequence ret
>integer y
>ret = repeat(repeat(0,rect[3]-rect[1]),rect[4]-rect[2])
>y = 1
>
>for i = rect[2] to rect[4]-1 do -- To the height of the cropping rect
> ret[y][1..rect[3]-rect[1]] = bmp[2][i][rect[1]..rect[3]-1]
> y = y + 1
>end for
>return ret
>end function
>
>
>mine:
>
>global function crop(sequence bmp,integer x,integer y,integer
>w,integer h)
> sequence s
> integer x2
> s = repeat(repeat(0,w),h)
> x2 = x+w-1
> for i = 1 to h do
> s[i] = bmp[y][x..x2]
> y += 1
> end for
> return s
>end function
>
>Much prettier, eh, pal?! Much faster too! I grabbed the first bitmap
>I spotted on my drive, a 320x200x256 pic, ran it through 1000
>iterations, removing a 20 pixel border from it, just for the heck of
>it. Your "Lightning-Fast", routine took 6.63 seconds, my plain effort
>just 3.49 seconds. I did not bother with any more tests, it's just not
>worth it. I hope even you can appreciate the difference. jiri
>
>Btw, your routine cheats: it does not show both the last column and
>the last row of pixels of the cropped image.;)
Jiri, I put your routine in my code, and only changed the parameters from
integers to a sequence (like my routine), now it seems that yours is slow
after all.
Here is your routine, with the parameters set like my routine, try it out:
global function cropBitmap(sequence bmp,sequence rect)
sequence s
integer x2
s = repeat(repeat(0,rect[3]),rect[4])
x2 = rect[1]+rect[3]-1
for i = 1 to rect[4] do
s[i] = bmp[rect[2]][rect[1]..rect[3]]
rect[2] = rect[2] + 1
end for
return s
end function
Mike The Spike
PS. Sequences are slower then integers...
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5. Re: Lightning-Fast Bitmap Cropping
- Posted by Mike The Spike <mikethespike2000 at HOTMAIL.COM>
Apr 15, 2000
-
Last edited Apr 16, 2000
Shit Jiri, your routine slows down a bit with the new parameters, but it's
still faster then mine...
So don't get me wrong or anything :)
Still, things realy fly in my code now! :)
Mike The Spike
PS. I'm using your "scale.e", it's quite fast aswell!
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6. Re: Lightning-Fast Bitmap Cropping
>Jiri, I put your routine in my code, and only changed the parameters
from
>integers to a sequence (like my routine), now it seems that yours is
slow
>after all.
Call it "Elementary Lesson in Euphoria Optimization", Chapter 2. ;)
jiri
7. Re: Lightning-Fast Bitmap Cropping
>Shit Jiri, your routine slows down a bit with the new parameters, but
it's
>still faster then mine...
:
>Still, things realy fly in my code now! :)
:
>PS. I'm using your "scale.e", it's quite fast aswell!
Finally we are making some progress! That's Chapter 3. (Never mind, I
am
probably a lousy teacher.) jiri
8. Re: Lightning-Fast Bitmap Cropping
> ---------------------- Information from the mail
header -----------------------
> Sender: Euphoria Programming for MS-DOS
<EUPHORIA at LISTSERV.MUOHIO.EDU>
> Poster: jiri babor <jbabor at PARADISE.NET.NZ>
> Subject: Re: Lightning-Fast Bitmap Cropping
> --------------------------------------------------------------------------
-----
>
<SNIP>
>
> Finally we are making some progress! That's Chapter 3. (Never mind, I
> am
> probably a lousy teacher.) jiri
>
Not much in each chapter. Do you have test after each chapter? :)
just a friendly poke.
Lucius L. Hilley III
