XLAV BTTH01b Cac Thao dTac Co Ban

Lab 0: Lm quen cc thao tc c bn v x l nh s v video s bng ngn ng C++/C#

Ni dung [C#] ............................................................................................................................................1

nh .............................................................................................................................................1

Load nh v hin th ................................................................................................................1

Truy xut n cc im nh .....................................................................................................1

Gii phng d liu nh khi khng s dng na ........................................................................3

Lu nh ...................................................................................................................................3

Video ..........................................................................................................................................3

Cng c lp trnh .....................................................................................................................3

Khi to ..................................................................................................................................3

Thit lp thng tin ...................................................................................................................3

Trch frame .............................................................................................................................3

Ghi file video ..........................................................................................................................4

[C++ & OpenCV] .......................................................................................................................5

Phin bn ....................................................................................................................................5

Cu hnh .....................................................................................................................................5

Chng trnh minh ha............................................................................................................5

nh .............................................................................................................................................5

To nh mi ............................................................................................................................5

Load nh .................................................................................................................................6

To ca s hin th nh ............................................................................................................6

Gii phng vng nh ...............................................................................................................6

Truy xut n cc pixel ca nh...............................................................................................6

Cch 1: ................................................................................................................................6

BI TP THC HNH X L NH S V VIDEO S

2 [email protected]

Cch 2: ................................................................................................................................7

Lu nh ...................................................................................................................................7

Video ..........................................................................................................................................8

Load d liu video t file hoc t webcam ..............................................................................8

Trch tng khung hnh (frame) v hin th ln mn hnh ..........................................................8

Gii phng vng nh ...............................................................................................................8

Ghi ni dung file video xung file ...........................................................................................8

Cch t chc chng trnh ..........................................................................................................9

Bi tp tho lun trn din n .................................................................................................. 11

Bi tp lp trnh ......................................................................................................................... 11

Ti liu tham kho..................................................................................................................... 12


1 [email protected]

[C#]

nh

Tool: C#

Load nh v hin th Gi s c mt PictureBox t tn pb_img.

Bitmap bm = new Bitmap([ng dn]); pb_img.Image = bm;

Truy xut n cc im nh Color c = bm.GetPixel(10, 10);

Mt im nh hin th trn mn hnh thng c 3 thnh phn mu.

for (int i = 0 ; i < bm.Width; i++) for (int j = 0; j < bm.Height; j++) { //Ly tng im nh ti v tr i, j, im (0,0) l gc tri trn ca nh Color c = bm.GetPixel(i, j); //Ly tng thnh phn mu v x l, //vd: tng thnh phn mu ln 30 n v int r = Math.Min(c.R + 30, 255); int g = c.G; int b = c.B; //Cp nht gi tr pixel trong nh Color c1 = Color.FromArgb(r, g, b); bm.SetPixel(i, j, c1); }

Khi chy chng trnh s pht hin mt vn l chng trnh chy kh chm. l do ta lin

tc gi cc phng thc GetPixel v SetPixel truy xut n cc im nh. tng tc x

l, ta dng phng thc Lockbit lu tm d liu nh vo b nh v truy truy xut trc tip

n vng nh ny. Xem thm trong [1].

using System.Drawing.Imaging; public BitmapData LockBits( Rectangle rect, ImageLockMode flags, PixelFormat format VD: BitmapData bmd = bm.LockBits(new Rectangle(0, 0, bm.Width, bm.Height), System.Drawing.Imaging.ImageLockMode.ReadWrite, bm.PixelFormat);


2 [email protected]

Lp BitmapData c cc thnh phn quan trng cn lu nh sau:

Scan0 Con tr lu a ch vng nh cha d liu nh.

Stride Kch thc ca 1 dng d liu nh (tnh bng byte), lun chia ht cho 4, nu thiu th

chng trnh s thm vi byte trng vo cui mi dng (Padding).

PixelFormat nh dng im nh:

o Format32BppArgb: Mi im nh chim 4 byte gm Red-Green-Blue-Alpha. Truy xut d

liu ca im nh ton (x,y) theo cng thc:

Scan0+(y * stride)+(x*4)

o Format24BppRgb: Mi im nh chim 3 byte gm Red-Green-Blue

Truy xut d liu ca im nh ton (x,y) theo cng thc:

Scan0+(y*Stride)+(x*3)

o Format8BppIndexed: Mi im nh biu din bi 1 byte tng ng vi v tr trong bng

mu.

Truy xut d liu ca im nh ton (x,y) theo cng thc:

Scan0+(y*Stride)+x

o Cc nh dng Format4BppIndexed, Format1BppIndexed sinh vin t tm hiu thm.

Width Chiu rng ca vng nh c lock.

Height Chiu di ca vng nh c lock.

V d:

BitmapData bmd = bm.LockBits(new Rectangle(0, 0, bm.Width, bm.Height), System.Drawing.Imaging.ImageLockMode.ReadWrite, bm.PixelFormat); int iPixelSize=3; switch (bm.PixelFormat) { case PixelFormat.Format32bppArgb: iPixelSize = 4; break; case PixelFormat.Format24bppRgb: iPixelSize = 3; break; case PixelFormat.Format8bppIndexed: iPixelSize = 1; break;


3 [email protected]

} unsafe //Nhp phi vo tn Project -> Property -> Unsafe code { for (int y = 0; y < bmd.Height; y++) { byte* row = (byte*)bmd.Scan0 + (y * bmd.Stride); for (int x = 0; x < bmd.Width; x++) { row[x * iPixelSize] = 255; } } } bm.UnlockBits(bmd);

Gii phng d liu nh khi khng s dng na Gi phng thc bm.Dispose(); nhanh chng gii phng vng nh khng s dng na.

Lu nh S dng phng thc bm.Save([ng dn]); lu nh.

Video

Cng c lp trnh

Emgu 2.2. Xem hng dn v ci t v cu hnh trong file hng dn trn din n.

Khi to Thm vo cc th vin cn thit

using Emgu.CV;

using Emgu.Util;

using Emgu.CV.UI;

using Emgu.CV.CvEnum;

using Emgu.CV.Structure;

Load file video

Image img; Capture c = new Emgu.CV.Capture("D:\\test.avi");

Thit lp thng tin Mun ly mt s thng tin v file video, dng phng thc GetCaptureProperty v SetCaptureProperty, v d mun ly s lng frame trong file video

int numFrame = (int)c.GetCaptureProperty(CAP_PROP.CV_CAP_PROP_FRAME_COUNT);

Trch frame

Cch 1:

CvInvoke.cvNamedWindow("1");

for (int i = 0; i < numFrame; i += 10)


4 [email protected]

{ //Di chuyn ti frame th i c.SetCaptureProperty(CAP_PROP.CV_CAP_PROP_POS_FRAMES, i); img = c.QueryFrame(); //Show the image CvInvoke.cvShowImage("1", img.Ptr); //Wait for the key pressing event CvInvoke.cvWaitKey(40); } c.Dispose();

CvInvoke.cvDestroyWindow("1");

Cch 2: Gi hm ca OpenCV thng qua phng thc CvInvoke

public static void GramFrame2()

{

IntPtr c = CvInvoke.cvCreateFileCapture("D:\\test.avi");

IntPtr Frame = new IntPtr();

int FrmNum = 0;

while ((Frame = CvInvoke.cvQueryFrame(c)) != (IntPtr)null)

{

FrmNum++;

if (FrmNum == 1)

{

Size size = CvInvoke.cvGetSize(Frame);

}

else

{

CvInvoke.cvNamedWindow("1");

CvInvoke.cvShowImage("1", Frame);

CvInvoke.cvWaitKey(40);

}

}

CvInvoke.cvReleaseCapture(ref c);

CvInvoke.cvReleaseCapture(ref Frame);

}

Ghi file video

public static void WriteVideo()

{

Image src;

Capture c = new Emgu.CV.Capture("test.avi");

int numFrame = (int)c.GetCaptureProperty(CAP_PROP.CV_CAP_PROP_FRAME_COUNT);

VideoWriter vw = new VideoWriter("out.avi", 30, c.Width, c.Height, true);

for (int i = 0; i < numFrame; i += 10)

{

c.SetCaptureProperty(CAP_PROP.CV_CAP_PROP_POS_FRAMES, i);

src = c.QueryFrame();

vw.WriteFrame(src);

}

src.Dispose();

vw.Dispose();

c.Dispose();

}


5 [email protected]

[C++ & OpenCV]

Phin bn

S dng phin bn OpenCV 2.2.

Cu hnh Xem trong file hng dn cu hnh trn din n.

Chng trnh minh ha

G th on chng trnh sau v xem kt qu

#include "cv.h" #include "cxcore.h" #include "highgui.h" void main() { IplImage *img = cvLoadImage([ng dn n file nh]); cvNamedWindow("MyImageWindow",1); cvShowImage("MyImageWindow",img); cvWaitKey(); cvDestroyWindow("MyImageWindow"); cvReleaseImage(&img); }

nh

To nh mi //To nh c kch thc nh nh, //mi pixel biu din bng 1 byte c gi tr unsigned int //ch c 1 knh mu IplImage* img1=cvCreateImage(cvSize(640,480),IPL_DEPTH_8U,1);

//To nh c 3 knh (thnh phn) mu: Blue-Green-Red //Gi tr ca mi thnh phn mu ti mi pixel l s thc IplImage* img2=cvCreateImage(cvSize(640,480),IPL_DEPTH_32F,3); //Sao chp nh ban u sang nh mi IplImage* img3; img3=cvCloneImage(img1);

P0 P1 P2 ...

nh grayscale nh mu c s dng

B0 G0 R0 B1 G1 R1

B2 G2 R2 ...

padding


6 [email protected]

padding mode (c th c hoc khng)

Load nh IplImage *img = cvLoadImage([ng dn n file nh]);

To ca s hin th nh cvNamedWindow("MyImageWindow",1); cvShowImage("MyImageWindow",img);

Gii phng vng nh

Sau khi ngi dng bm phm bt k tt ca s nh, nu khng s dng na th ta gii phng

vng nh.

cvDestroyWindow("MyImageWindow"); //Gii phng vng nh ca ca s nh cvReleaseImage(&img); // Gii phng vng nh cp cho nh

Truy xut n cc pixel ca nh

Gi s ta cn truy xut n knh (thnh phn) mu th k ca pixel dng i v ct j trong nh.

Cch 1:

D hiu, nhng chm do khng truy xut trc tip m thng qua cc hm x l.

//i vi nh n sc (ch c 1 knh mu) //v gi tr mu ca mi pixel l s nguyn: img=cvCreateImage(...,IPL_DEPTH_8U,1) CvScalar s; // Ly gi tr im nh ta (i,j) s=cvGet2D(img,i,j); printf("Gi tr mu ca im nh ny = %d",s.val[0]); //Gn gi tr im nh ti ta (i,j) s.val[0]=111; //thay i gi tr im nh cvSet2D(img,i,j,s); //i vi nh mu (c 3 knh mu) //v gi tr mu ca mi thnh phn mu ti mi im nh l s thc //img=cvCreateImage(...,IPL_DEPTH_32F,3) //Mi im nh biu din bi 3 byte tng ng vi 3 thnh phn mu Blue-Green-Red ca im nh //Cc thnh phn ca cc im nh c lu theo th t nh sau: B1 G1 R1 B2 G2 R2 ... CvScalar s; // Ly gi tr im nh ta (i,j) s=cvGet2D(img,i,j); printf("B=%f, G=%f, R=%f\n",s.val[0],s.val[1],s.val[2]); // Gn gi tr cho im nh ti ta (i,j) s.val[0]=111; // gi tr mu cho thnh phn Blue s.val[1]=111; // gi tr mu cho thnh phn Green


7 [email protected]

s.val[2]=111; // gi tr mu cho thnh phn Red cvSet2D(img,i,j,s);

Cch 2:

Phc tp hn, nhng nhanh hn.

//i vi nh n sc (ch c 1 knh mu) //v gi tr mu ca mi pixel l s nguyn: img=cvCreateImage(...,IPL_DEPTH_8U,1) int height = img->height; int width = img->width; //Tnh s pixel trn mi dng, //bi v mt s nh s dng padding mode nn step c th khc width int step = img->widthStep/sizeof(uchar); //Ly a ch ca vng nh cha d liu nh uchar* data = (uchar *)img->imageData; //Thay i gi tr im nh ti ta (i,j) data[i*step+j] = 111;

//i vi nh mu (c 3 knh mu) //v gi tr mu ca mi knh ti mi im nh l s nguyn: //img = cvCreateImage(cvSize(...),IPL_DEPTH_8U,3) int height = img->height; int width = img->width; //Tnh s pixel trn mi dng, //bi v mt s nh s dng padding mode nn step c th khc width int step = img->widthStep/sizeof(uchar); //S lng knh (thnh phn) mu int channels = img->nChannels; uchar* data = (uchar *)img->imageData; //Thay i gi tr thnh phn mu th k (k=0 l blue, k=1 l green, k=2 l red) // ca im nh ti ton (i,j) data[i*step+j*channels+k] = 111; //i vi nh mu (c 3 knh mu) //v gi tr mu ca mi knh ti mi im nh l s thc //img=cvCreateImage(...,IPL_DEPTH_32F,3) int height = img->height; int width = img->width; //Tnh s pixel trn mi dng, //bi v mt s nh s dng padding mode nn step c th khc width int step = img->widthStep/sizeof(float); int channels = img->nChannels; //Ch , con tr s thc float * data = (float *)img->imageData; data[i*step+j*channels+k] = 111;

Ngoi ra cn c cch truy xut khc hiu qu hn, sinh vin t tham kho trong ti liu ...

Lu nh cvSaveImage(C:\\Test.jpg,pImg);


8 [email protected]

Video

Load d liu video t file hoc t webcam CvCapture *cap = cvCaptureFromCAM(0); //t webcam CvCapture *cap = cvCaptureFromAVI([ng dn n file video]);

Trch tng khung hnh (frame) v hin th ln mn hnh IplImage *img = 0; cvNamedWindow("Image:",1); while (1) { /* CCH 1 if (!cvGrabFrame(cap)) { printf("cannot grab\n"); exit(0); } img = cvRetrieveFrame(cap); */ // CCH 2 img = cvQueryFrame(cap); //Bin img s c ti s dng trch frame khc //nn cha release trong y c. if (!img) { printf("cannot grab\n"); exit(0); } // Gi hm x l g y, vd: kh nhiu, chuyn thnh nh trng en... // Nn copy nh gc sang mt nh khc ri mi x l. // Sau hin th frame x l ln mn hnh // 1 giy 24 khung hnh ==> 1 khung hnh ~ 40 mili giy cvShowImage("Image:",img); cvWaitKey(40); //Th b dng ny coi chuyn g xy ra!! }

Gii phng vng nh

Khi no khng s dng na th nh gii phng vng nh

cvDestroyWindow("Image:"); cvReleaseImage(&img); cvReleaseCapture(&cap);

Ghi ni dung file video xung file //M file cn x l ra CvCapture *input = cvCaptureFromAVI("E:\\Entertainment\\Clips\\test.avi"); //s dng 1 bin ly thng tin v kch thc ca mi frame IplImage* image = cvRetrieveFrame(input); if (!image) {


9 [email protected]

printf("Unable to read input"); return 0; } //Ly kch thc ca frame CvSize imgSize; imgSize.width = image->width; imgSize.height = image->height; //Thy thng tin v s lng khung hnh/giy (frame per second) double fps = cvGetCaptureProperty( input, CV_CAP_PROP_FPS ); //Khai bo 1 bin ghi xung file video c nh dng tng t file gc //s dng b m ha motion-jpeg nn cc frame CvVideoWriter *writer = cvCreateVideoWriter( "E:\\Entertainment\\Clips\\out.avi", CV_FOURCC('M', 'J', 'P', 'G'), fps, imgSize ); IplImage* colourImage; for (;;) { //Trch tng khung hnh ra colourImage = cvQueryFrame(input); if (!colourImage) { printf("cannot grab\n"); break; } //Gi hm x l cho colourImage y //Nn copy sang mt bin khc x l //Sau ghi vo file cvWriteFrame(writer, colourImage); }

Cch t chc chng trnh Chng trnh phi c t chc thnh cc lp i tng. Di y l mt v d mu vit bng

C#.

public class ImageShowing { public Bitmap myBitmap; // Cc thuc tnh khc (nu c) public ImageShowing() {//Dng khi to gi tr ban u; myBitmap = null; } public ImageShowing(Bitmap bm) {//Hm dng sao chp Bitmap myBitmap = bm;


10 [email protected]

} //Cc hm dng khc //Cc phng thc truy cp n cc thuc tnh public Bitmap MyBitmap { get { return myBitmap; } set { if (value != null) myBitmap = value; } } //Cc hm x l nh public int LoadBitmap(string strFileName) { if (strFileName.CompareTo("") != 0) { myBitmap = new Bitmap(strFileName); return 1; } return 0; } //V cc hm bin i nh khc (nu c) ~ImageShowing() {//T gii phng vng nh khi ko xi na if (myBitmap != null) myBitmap.Dispose(); } } public partial class Image_Processing : Form { ImageShowing imShow; public Image_Processing() { InitializeComponent(); imShow = new ImageShowing(); } private void bt_LoadImg_Click(object sender, EventArgs e) { openFileDialog1.InitialDirectory = ".."; if (openFileDialog1.ShowDialog() == DialogResult.OK) { if (imShow.LoadBitmap(openFileDialog1.FileName) != 0) MessageBox.Show("ng dn sai"); } } ... }



Bi tp tho lun trn din n

1. Trong phn X l video bng OpenCV c 2 cch trch khung hnh. Tm hiu v tho lun

xem 2 cch ny khc nhau ch no?

2. Dng hm cvCreateImage, ln lt to ra cc nh c kch thc bng nhau theo nh dng:

IPL_DEPTH_8U (unsigned byte)

IPL_DEPTH_8S (byte)

IPL_DEPTH_16U

IPL_DEPTH_16S

IPL_DEPTH_32S

IPL_DEPTH_32F (float)

IPL_DEPTH_64F Kho st gi tr width v step ca mi loi.

Bi tp lp trnh

Sinh vin c php s dng cc hm chuyn i c sn.

1. Vit chng trnh hin th nh c kch thc bt k. Thay i kch thc nh sao cho hin th

va trong vng c kch thc 200x200.

2. Vit chng trnh ti ln 1 file avi mu, chuyn frame thnh nh xm v hin th ra mn hnh.

Cc file avi c th download ti a ch http://www.jhepple.com/support/sample_movies1.htm



Ti liu tham kho

[1] Bob Powell, Cch LockBits truy xut d liu nh trong C#,

http://www.bobpowell.net/lockingbits.htm, 2011.

[2] Microsoft, Microsoft Developer Network, http://msdn.microsoft.com, 2011.

[3] Din n lp 51TH1, trng H Nha Trang, Setup v config OpenCV 2.2,

http://51th1.com/read.php?5, 2011.

[4] Gady Agam, Introduction to programming with OpenCV: Accessing image elements,

http://www.cs.iit.edu/~agam/cs512/lect-notes/opencv-intro/opencv-intro.html, 2006

[5] Weis, OpenCV: capture the frame, http://blog.weisu.org/2007/12/opencv-capture-frame.html,

2007.

[6] Stackoverflow, Writing avi files in OpenCV,

http://stackoverflow.com/questions/368967/writing-avi-files-in-opencv, 2011.

[7] Saida Bouakaz, GUI and Video Acquisition Reference, http://www710.univ-

lyon1.fr/~bouakaz/OpenCV-0.9.5/docs/ref/OpenCVRef_Highgui.htm#decl_cvWriteToAVI,

?.

[8] Leeds Guide to OpenCV , Saving Movies,

http://www.comp.leeds.ac.uk/vision/opencv/movies.html, 2006.

[9] Robert Laganire, Programming computer vision applications: A step by step guide to the

use of Microsoft Visual C++ and the Intel OpenCV library,

http://www.site.uottawa.ca/~laganier/tutorial/opencv+directshow/cvision.htm, 2009.

[10] EmguCV, EmguCV Tutorial, http://www.emgu.com/wiki/index.php/Tutorial, 2010.

[11] Programmers united develop net, Capture video using Emgu,

http://read.pudn.com/downloads190/sourcecode/graph/texture_mapping/892527/Capture.cs

__.htm, 2011.

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XLAV BTTH01b Cac Thao dTac Co Ban