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Peter Fagerbrant
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 Posted: Wed Jan 19, 2005 1:27 pm Post subject: Slow scanline |
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I am using a USB camera with a framecapture rate of 30 fps. The camera
deliver the graphics as a jpeg image and I have to convert it to 8 bit
greyscaled bitmap and store in arrays.
I Use this for storing the bitmapinfo in a array:
for( int y=0;y<CAMRESY;y++){
xoffsIn = 0;
BYTE* pLine = (BYTE*) ((THackJPEGImage*)JPEGImage)->Bitmap->ScanLine[y];
for( int x=0;x
int r = pLine[ xoffsIn + 0];
int g = pLine[ xoffsIn + 1];
int b = pLine[ xoffsIn + 2];
int iGrey = b*0.11 + g*0.59 + r*0.30;
pData8Out[ x + yoffsOut ] = iGrey;
xoffsIn += 3;
}
yoffsIn += CAMRESX+CAMRESX+CAMRESX;
yoffsOut += CAMRESX;
}
I do it in realtime. Unfortenly its impacts performens more then I want. The
camera delivers 30 fps and with this aproach I can only process 12-15 fps.
Is there a faster way to do this? I need more then 15fps. I would bee happy
with 20fps.
Anyone who has a clue?
Scanline consumes to much of the proccessingpower I need.
Best reg.
Peter Fagerbrant
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Jonathan Benedicto
Guest
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| Posted: Wed Jan 19, 2005 6:45 pm Post subject: Re: Slow scanline |
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What is pData8Out ?
I tried to do some tweaking with your code, and by trimming out all the
xoffsIn, yOffsIn and yOffsOut and removing the pData8Out line, I was able to
achieve a simulated 83-85 fps.
To do this sim, I used a 640x480 jpeg, and used a for loop to simulate 1000
frames being processed.
But to be able to really tweak your code, I need to know how your are
storing the grey values into the pData8Out array.
--
Jonathan
"Peter Fagerbrant" <peter (AT) fagerbrant (DOT) com> wrote
| Quote: | I am using a USB camera with a framecapture rate of 30 fps. The camera
deliver the graphics as a jpeg image and I have to convert it to 8 bit
greyscaled bitmap and store in arrays.
I Use this for storing the bitmapinfo in a array:
for( int y=0;y<CAMRESY;y++){
xoffsIn = 0;
BYTE* pLine = (BYTE*) ((THackJPEGImage*)JPEGImage)->Bitmap->ScanLine[y];
for( int x=0;x
int r = pLine[ xoffsIn + 0];
int g = pLine[ xoffsIn + 1];
int b = pLine[ xoffsIn + 2];
int iGrey = b*0.11 + g*0.59 + r*0.30;
pData8Out[ x + yoffsOut ] = iGrey;
xoffsIn += 3;
}
yoffsIn += CAMRESX+CAMRESX+CAMRESX;
yoffsOut += CAMRESX;
}
I do it in realtime. Unfortenly its impacts performens more then I want.
The
camera delivers 30 fps and with this aproach I can only process 12-15 fps.
Is there a faster way to do this? I need more then 15fps. I would bee
happy with 20fps.
Anyone who has a clue?
Scanline consumes to much of the proccessingpower I need.
Best reg.
Peter Fagerbrant
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Peter Fagerbrant
Guest
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| Posted: Wed Jan 19, 2005 8:22 pm Post subject: Re: Slow scanline |
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Jonathan Benedicto wrote:
| Quote: | What is pData8Out ?
I tried to do some tweaking with your code, and by trimming out all the
xoffsIn, yOffsIn and yOffsOut and removing the pData8Out line, I was able to
achieve a simulated 83-85 fps.
To do this sim, I used a 640x480 jpeg, and used a for loop to simulate 1000
frames being processed.
But to be able to really tweak your code, I need to know how your are
storing the grey values into the pData8Out array.
pData8Out is just a pointer to a bigger array |
struct CAPIMAGE
{
DWORD dwTime;
BYTE Data[CAMRESX*CAMRESY]; //640x480
};
pImages = new CAPIMAGE[MAXIMAGES]; //MAXIMAGES=50
BYTE* pData8Out = pImages[iIndex].Data;
I use index as the index of captured frames.
Without the for( int y=0;y<CAMRESY;y++) {...}
It runs with 26-30 fps. (Near max of the camera output)
When I comment out the for( int x=0;x
but keeps y loop including BYTE* pLine = (BYTE*)
((THackJPEGImage*)JPEGImage)->Bitmap->ScanLine[y];
It drops to 15fps.
When I commenting out the "JPEGImage)->Bitmap->ScanLine[y];"
Enabling the x loop but only do:
for( int x=0;x
{
int r = 11; //pLine[ xoffsIn + 0];
int g = 11; //pLine[ xoffsIn + 1];
int b = 11; //pLine[ xoffsIn + 2];
int iGrey = b*0.11 + g*0.59 + r*0.30;
pData8Out[ x + yoffsOut ] = iGrey;
xoffsIn += 3;
}
It runs on 22-26 fps
This is my testrunnings from today.
Best reg.
Peter Fagerbrant
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Peter Fagerbrant
Guest
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| Posted: Wed Jan 19, 2005 8:48 pm Post subject: Re: Slow scanline |
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And in the callbackfunction I fill the JPEGImage with the below code
before my call to the function "storeGrayScale2Bitmap"
BYTE *MemPtr = lpVHdr->lpData;
stream->Write(MemPtr, lpVHdr->dwBytesUsed);
stream->Position = 0;
JPEGImage->LoadFromStream ( stream );
reg/
PFa
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Jonathan Benedicto
Guest
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| Posted: Wed Jan 19, 2005 11:06 pm Post subject: Re: Slow scanline |
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I think that you might be able to do a couple things to get faster
framerate.
The first thing is maybe to get the bitmap bits into a BYTE array instead of
calling ScanLine. Eg. use something like GetDIBits or somethings like that
to directly access the data.
Then you could also globalize all of your int and BYTE declarations in that
function.
And maybe, don't use those xoffsIn, yOffsIn and yOffsOut variables, but
rather use the x and y variables. This is so that you can reduce the amount
of math the chip does.
--
Jonathan
"Peter Fagerbrant" <peter (AT) fagerbrant (DOT) com> wrote
| Quote: | Jonathan Benedicto wrote:
What is pData8Out ?
I tried to do some tweaking with your code, and by trimming out all the
xoffsIn, yOffsIn and yOffsOut and removing the pData8Out line, I was able
to achieve a simulated 83-85 fps.
To do this sim, I used a 640x480 jpeg, and used a for loop to simulate
1000 frames being processed.
But to be able to really tweak your code, I need to know how your are
storing the grey values into the pData8Out array.
pData8Out is just a pointer to a bigger array
struct CAPIMAGE
{
DWORD dwTime;
BYTE Data[CAMRESX*CAMRESY]; //640x480
};
pImages = new CAPIMAGE[MAXIMAGES]; //MAXIMAGES=50
BYTE* pData8Out = pImages[iIndex].Data;
I use index as the index of captured frames.
Without the for( int y=0;y<CAMRESY;y++) {...}
It runs with 26-30 fps. (Near max of the camera output)
When I comment out the for( int x=0;x
but keeps y loop including BYTE* pLine = (BYTE*)
((THackJPEGImage*)JPEGImage)->Bitmap->ScanLine[y];
It drops to 15fps.
When I commenting out the "JPEGImage)->Bitmap->ScanLine[y];"
Enabling the x loop but only do:
for( int x=0;x
{
int r = 11; //pLine[ xoffsIn + 0];
int g = 11; //pLine[ xoffsIn + 1];
int b = 11; //pLine[ xoffsIn + 2];
int iGrey = b*0.11 + g*0.59 + r*0.30;
pData8Out[ x + yoffsOut ] = iGrey;
xoffsIn += 3;
}
It runs on 22-26 fps
This is my testrunnings from today.
Best reg.
Peter Fagerbrant
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KL Chin
Guest
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| Posted: Thu Jan 20, 2005 1:07 am Post subject: Re: Slow scanline |
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Hi,
Try to use pre-calaculate result for
int iGrey = b*0.11 + g*0.59 + r*0.30;
into grgb[3][256];
iGrey = grgb[0][r] + grgb[1][g] + grgb[2][b];
Regards
KL Chin
"Peter Fagerbrant" <peter (AT) fagerbrant (DOT) com> wrote
| Quote: | Jonathan Benedicto wrote:
What is pData8Out ?
I tried to do some tweaking with your code, and by trimming out all the
xoffsIn, yOffsIn and yOffsOut and removing the pData8Out line, I was able
to achieve a simulated 83-85 fps.
To do this sim, I used a 640x480 jpeg, and used a for loop to simulate
1000 frames being processed.
But to be able to really tweak your code, I need to know how your are
storing the grey values into the pData8Out array.
pData8Out is just a pointer to a bigger array
struct CAPIMAGE
{
DWORD dwTime;
BYTE Data[CAMRESX*CAMRESY]; //640x480
};
pImages = new CAPIMAGE[MAXIMAGES]; //MAXIMAGES=50
BYTE* pData8Out = pImages[iIndex].Data;
I use index as the index of captured frames.
Without the for( int y=0;y<CAMRESY;y++) {...}
It runs with 26-30 fps. (Near max of the camera output)
When I comment out the for( int x=0;x
but keeps y loop including BYTE* pLine = (BYTE*)
((THackJPEGImage*)JPEGImage)->Bitmap->ScanLine[y];
It drops to 15fps.
When I commenting out the "JPEGImage)->Bitmap->ScanLine[y];"
Enabling the x loop but only do:
for( int x=0;x
{
int r = 11; //pLine[ xoffsIn + 0];
int g = 11; //pLine[ xoffsIn + 1];
int b = 11; //pLine[ xoffsIn + 2];
int iGrey = b*0.11 + g*0.59 + r*0.30;
pData8Out[ x + yoffsOut ] = iGrey;
xoffsIn += 3;
}
It runs on 22-26 fps
This is my testrunnings from today.
Best reg.
Peter Fagerbrant
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Peter Fagerbrant
Guest
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| Posted: Thu Jan 20, 2005 9:08 am Post subject: Re: Slow scanline |
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"KL Chin" <klchin (AT) 1asia (DOT) com.my> skrev i meddelandet
news:41ef0469 (AT) newsgroups (DOT) borland.com...
| Quote: | Hi,
Try to use pre-calaculate result for
int iGrey = b*0.11 + g*0.59 + r*0.30;
into grgb[3][256];
iGrey = grgb[0][r] + grgb[1][g] + grgb[2][b];
The LUT gives me about one fps extra in speed. |
Its a bit on the right way
Thanks.
reg/
PFa
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Peter Fagerbrant
Guest
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| Posted: Thu Jan 20, 2005 9:13 am Post subject: Re: Slow scanline |
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"Jonathan Benedicto" <incorrect (AT) no (DOT) server> skrev i meddelandet
news:41eee7f7$1 (AT) newsgroups (DOT) borland.com...
| Quote: | I think that you might be able to do a couple things to get faster
framerate.
The first thing is maybe to get the bitmap bits into a BYTE array instead
of calling ScanLine. Eg. use something like GetDIBits or somethings like
that to directly access the data.
I cleaning the mathroutine. |
I't sounds like GetDIBits is a solution. From what I seen in this
discussions, the scanline recreates the bitmap for every call. Its a waste
in my case. If I could have the bitmaparray in one pice and traverse it,
naturily it would be much faster.
I'l dig a bit about how to use the GetDIBits in my case.
Reg/
PFa
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Hans Galema
Guest
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| Posted: Thu Jan 20, 2005 10:02 am Post subject: Re: Slow scanline |
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Jonathan Benedicto wrote:
| Quote: | And maybe, don't use those xoffsIn, yOffsIn and yOffsOut variables, but
rather use the x and y variables. This is so that you can reduce the amount
of math the chip does.
|
You mean something like:
for( int y=0;y<CAMRESY;y++){
BYTE* pLine = (BYTE*) ((THackJPEGImage*)JPEGImage)->Bitmap->ScanLine[y];
for( int x=0;x
int r = *pLine++;
int g = *pLine++;
int b = *pLine++;
int iGrey = .....
pData8Out[ x + yoffsOut ] = iGrey;
}
}
One could use a pointer for pDat8Out too.
Please trim quotes. You even triple them.
Hans.
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Jonathan Benedicto
Guest
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| Posted: Thu Jan 20, 2005 3:37 pm Post subject: Re: Slow scanline |
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I'm sorry for not trimming the quotes.
I was thinking of something like this :
int x, iGrey, xl = CAMRESX * 3;
float r, g, b;
BYTE* pLine;
for(int y=0;y<CAMRESY;y++){
pLine = (BYTE*) ((THackJPEGImage*)JPEGImage)->Bitmap->ScanLine[y];
for(x=0;x<xl;x+=3){
r = pLine[x];
g = pLine[x + 1];
b = pLine[x + 2];
iGrey = b * 0.11 + g * 0.59 + r * 0.30;
pData8Out[(x / 3) + yoffsOut] = iGrey;
}
yoffsOut += CAMRESX;
}
--
Jonathan
"Hans Galema"
| Quote: | You mean something like:
Hans.
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