Increasing camera capture resolution in OpenCV

Question

In my C/C++ program, I'm using OpenCV to capture images from my webcam. The camera (Logitech QuickCam IM) can capture at resolutions 320x240, 640x480 and 1280x960. But, for some strange reason, OpenCV gives me images of resolution 320x240 only. Calls to change the resolution using cvSetCaptureProperty() with other resolution values just don't work. How do I capture images with the other resolutions possible with my webcam?

Collegian

Note: a common misuse of the term "resolution" is referring to it as the number of pixels in an image.This is NOT how various standards describe it. Resolution is closely related to the SIZE of pixels and not their NUMBER. You can have a 10MP image with a bad resolution or a 1MP with high resolution. Even the documentation of OpenCV lucky enough does not do this mistake. In fact if you for example go to docs.opencv.org/modules/superres/doc/super_resolution.html and look at the references at the bottom you will see that image resolution is clearly distinguished from the number of pixels. – Berkelium

Answer 1

There doesn't seem to be a solution. The resolution can be increased to 640x480 using this hack shared by lifebelt77. Here are the details reproduced:

Add to highgui.h:

#define CV_CAP_PROP_DIALOG_DISPLAY 8
#define CV_CAP_PROP_DIALOG_FORMAT 9
#define CV_CAP_PROP_DIALOG_SOURCE 10
#define CV_CAP_PROP_DIALOG_COMPRESSION 11
#define CV_CAP_PROP_FRAME_WIDTH_HEIGHT 12

Add the function icvSetPropertyCAM_VFW to cvcap.cpp:

static int icvSetPropertyCAM_VFW( CvCaptureCAM_VFW* capture, int property_id, double value )
{
    int result = -1;
    CAPSTATUS capstat;
    CAPTUREPARMS capparam;
    BITMAPINFO btmp;

    switch( property_id )
    {
        case CV_CAP_PROP_DIALOG_DISPLAY:
            result = capDlgVideoDisplay(capture->capWnd);
            //SendMessage(capture->capWnd,WM_CAP_DLG_VIDEODISPLAY,0,0);
            break;

        case CV_CAP_PROP_DIALOG_FORMAT:
            result = capDlgVideoFormat(capture->capWnd);
            //SendMessage(capture->capWnd,WM_CAP_DLG_VIDEOFORMAT,0,0);
            break;

        case CV_CAP_PROP_DIALOG_SOURCE:
            result = capDlgVideoSource(capture->capWnd);
            //SendMessage(capture->capWnd,WM_CAP_DLG_VIDEOSOURCE,0,0);
            break;

        case CV_CAP_PROP_DIALOG_COMPRESSION:
            result = capDlgVideoCompression(capture->capWnd);
            break;

        case CV_CAP_PROP_FRAME_WIDTH_HEIGHT:
            capGetVideoFormat(capture->capWnd, &btmp, sizeof(BITMAPINFO));
            btmp.bmiHeader.biWidth = floor(value/1000);
            btmp.bmiHeader.biHeight = value-floor(value/1000)*1000;
            btmp.bmiHeader.biSizeImage = btmp.bmiHeader.biHeight *
            btmp.bmiHeader.biWidth * btmp.bmiHeader.biPlanes *
            btmp.bmiHeader.biBitCount / 8;
            capSetVideoFormat(capture->capWnd, &btmp, sizeof(BITMAPINFO));
            break;

        default:
            break;
    }

    return result;
}

and edit captureCAM_VFW_vtable as following:

static CvCaptureVTable captureCAM_VFW_vtable =
{
6,
(CvCaptureCloseFunc)icvCloseCAM_VFW,
(CvCaptureGrabFrameFunc)icvGrabFrameCAM_VFW,
(CvCaptureRetrieveFrameFunc)icvRetrieveFrameCAM_VFW,
(CvCaptureGetPropertyFunc)icvGetPropertyCAM_VFW,
(CvCaptureSetPropertyFunc)icvSetPropertyCAM_VFW, // was NULL
(CvCaptureGetDescriptionFunc)0
};

Now rebuilt highgui.dll.

Collegian

This method caps resolution at 640x480? – Oubliette

Answer 2

I'm using openCV 1.1pre1 under Windows (videoinput library is used by default by this version of openCv under windows).

With these instructions I can set camera resolution. Note that I call the old cvCreateCameraCapture instead of cvCaptureFromCam.

capture = cvCreateCameraCapture(cameraIndex);

cvSetCaptureProperty( capture, CV_CAP_PROP_FRAME_WIDTH, 640 );

cvSetCaptureProperty( capture, CV_CAP_PROP_FRAME_HEIGHT, 480 );


videoFrame = cvQueryFrame(capture);

I've tested it with Logitech, Trust and Philips webcams

Mantissa

Works for me too on OpenCV 1.1, and I'd recommend this to be the accepted answer. – Dystrophy

yep, I confirm this works for me too. The current accepted solution is not necessary. – Brooke

The docs say this isn't supported, but it even works at HD resolutions. However, if the requested resolution is not available from the camera, it falls back a default resolution silently. The current accepted solution is not necessary. – Bissonnette

check the return values from cvSetCapture Property not all cameras will accept the instruction – Dariadarian

Answer 3

I've done image processing in linux before and skipped OpenCV's built in camera functionality because it's (as you've discovered) incomplete.

Depending on your OS you may have more luck going straight to the hardware through normal channels as opposed to through openCV. If you are using Linux, video4linux or video4linux2 should give you relatively trivial access to USB webcams and you can use libavc1394 for firewire. Depending on the device and the quality of the example code you follow, you should be able to get the device running with the parameters you want in an hour or two.

Edited to add: You are on your own if its Windows. I imagine it's not much more difficult but I've never done it.

Glider

Answer 4

I strongly suggest using VideoInput lib, it supports any DirectShow device (even multiple devices at the same time) and is more configurable. You'll spend five minutes make it play with OpenCV.

Sluggard

Answer 5

Check this ticket out: https://code.ros.org/trac/opencv/ticket/376

"The solution is to use the newer libv4l-based wrapper.

1. install libv4l-dev (this is how it's called in Ubuntu)

2. rerun cmake, you will see "V4L/V4L2: Using libv4l"

3. rerun make. now the resolution can be changed. tested with built-in isight on MBP."

This fixed it for me using Ubuntu and might aswell work for you.

Overthrust

Where the cmake should be called? – Lifegiving

Dont remember now. opencv.willowgarage.com/wiki/InstallGuide opencv.willowgarage.com/wiki/InstallGuide%20%3A%20Debian Might help – Overthrust

Answer 6

Code I finally got working in Python once Aaron Haun pointed out I needed to define the arguments of the set function before using them.

#Camera_Get_Set.py
#By Forrest L. Erickson of VRX Company Inc. 8-31-12.
#Opens the camera and reads and reports the settings.
#Then tries to set for higher resolution.
#Workes with Logitech C525 for resolutions 960 by 720 and 1600 by 896


import cv2.cv as cv
import numpy

CV_CAP_PROP_POS_MSEC = 0
CV_CAP_PROP_POS_FRAMES = 1
CV_CAP_PROP_POS_AVI_RATIO = 2
CV_CAP_PROP_FRAME_WIDTH = 3
CV_CAP_PROP_FRAME_HEIGHT = 4
CV_CAP_PROP_FPS = 5
CV_CAP_PROP_POS_FOURCC = 6
CV_CAP_PROP_POS_FRAME_COUNT = 7
CV_CAP_PROP_BRIGHTNESS = 8
CV_CAP_PROP_CONTRAST = 9
CV_CAP_PROP_SATURATION = 10
CV_CAP_PROP_HUE = 11

CV_CAPTURE_PROPERTIES = tuple({
CV_CAP_PROP_POS_MSEC,
CV_CAP_PROP_POS_FRAMES,
CV_CAP_PROP_POS_AVI_RATIO,
CV_CAP_PROP_FRAME_WIDTH,
CV_CAP_PROP_FRAME_HEIGHT,
CV_CAP_PROP_FPS,
CV_CAP_PROP_POS_FOURCC,
CV_CAP_PROP_POS_FRAME_COUNT,
CV_CAP_PROP_BRIGHTNESS,
CV_CAP_PROP_CONTRAST,
CV_CAP_PROP_SATURATION,
CV_CAP_PROP_HUE})

CV_CAPTURE_PROPERTIES_NAMES = [
"CV_CAP_PROP_POS_MSEC",
"CV_CAP_PROP_POS_FRAMES",
"CV_CAP_PROP_POS_AVI_RATIO",
"CV_CAP_PROP_FRAME_WIDTH",
"CV_CAP_PROP_FRAME_HEIGHT",
"CV_CAP_PROP_FPS",
"CV_CAP_PROP_POS_FOURCC",
"CV_CAP_PROP_POS_FRAME_COUNT",
"CV_CAP_PROP_BRIGHTNESS",
"CV_CAP_PROP_CONTRAST",
"CV_CAP_PROP_SATURATION",
"CV_CAP_PROP_HUE"]


capture = cv.CaptureFromCAM(0)

print ("\nCamera properties before query of frame.")
for i in range(len(CV_CAPTURE_PROPERTIES_NAMES)):
#    camera_valeus =[CV_CAPTURE_PROPERTIES_NAMES, foo]
    foo = cv.GetCaptureProperty(capture, CV_CAPTURE_PROPERTIES[i])
    camera_values =[CV_CAPTURE_PROPERTIES_NAMES[i], foo]
#    print str(camera_values)
    print str(CV_CAPTURE_PROPERTIES_NAMES[i]) + ": " + str(foo)


print ("\nOpen a window for display of image")
cv.NamedWindow("Camera", 1)
while True:
    img = cv.QueryFrame(capture)
    cv.ShowImage("Camera", img)
    if cv.WaitKey(10) == 27:
        break
cv.DestroyWindow("Camera")


#cv.SetCaptureProperty(capture, CV_CAP_PROP_FRAME_WIDTH, 1024)
#cv.SetCaptureProperty(capture, CV_CAP_PROP_FRAME_HEIGHT, 768)
cv.SetCaptureProperty(capture, CV_CAP_PROP_FRAME_WIDTH, 1600)
cv.SetCaptureProperty(capture, CV_CAP_PROP_FRAME_HEIGHT, 896)


print ("\nCamera properties after query and display of frame.")
for i in range(len(CV_CAPTURE_PROPERTIES_NAMES)):
#    camera_valeus =[CV_CAPTURE_PROPERTIES_NAMES, foo]
    foo = cv.GetCaptureProperty(capture, CV_CAPTURE_PROPERTIES[i])
    camera_values =[CV_CAPTURE_PROPERTIES_NAMES[i], foo]
#    print str(camera_values)
    print str(CV_CAPTURE_PROPERTIES_NAMES[i]) + ": " + str(foo)


print ("/nOpen a window for display of image")
cv.NamedWindow("Camera", 1)
while True:
    img = cv.QueryFrame(capture)
    cv.ShowImage("Camera", img)
    if cv.WaitKey(10) == 27:
        break
cv.DestroyWindow("Camera")

Curule

Answer 7

I am using debian and ubuntu, i had the same problem, i couldn't change the resolution of video input using CV_CAP_PROP_FRAME_WIDTH and CV_CAP_PROP_FRAME_HEIGHT

I turned out that the reason was a missing library. I installed lib4l-dev through synaptic, rebuilt OpenCV and the problem is SOLVED!

Sungod

Answer 8

I am posting this to ensure that no one else wastes time on this setproperty function. I spent 2 days on this to see that nothing seems to be working. So I dug out the code (I had installed the library the first time around). This is what actually happens - cvSetCaptureProperty, calls setProperty inside CvCapture class and lo behold setProperty does nothing. It just returns false. Instead I'll pick up using another library to feed OpenCV a capture video/images. I am using OpenCV 2.2

Burst

Answer 9

I find that in Windows (from Win98 to WinXP SP3), OpenCV will often use Microsoft's VFW library for camera access. The problem with this is that it is often very slow (say a max of 15 FPS frame capture) and buggy (hence why cvSetCaptureProperty often doesn't work). Luckily, you can usually change the resolution in other software (particularly "AMCAP", which is a demo program that is easily available) and it will effect the resolution that OpenCV will use. For example, you can run AMCAP to set the resolution to 640x480, and then OpenCV will use that by default from that point onwards!

But if you can use a different Windows camera access library such as the "videoInput" library http://muonics.net/school/spring05/videoInput/ that accesses the camera using very efficient DirectShow (part of DirectX). Or if you have a professional quality camera, then often it will come with a custom API that lets you access the camera, and you could use that for fast access with the ability to change resolution and many other things.

Amadis

Answer 10

Under Windows try to use VideoInput library: http://robocraft.ru/blog/computervision/420.html

Biforked

Does VideoInput works to capture multiple exposure images? – Cooney

Answer 11

cvSetCaptureProperty( capture, CV_CAP_PROP_FRAME_WIDTH, WIDTH );

cvSetCaptureProperty( capture, CV_CAP_PROP_FRAME_HEIGHT, HEIGHT);

cvQueryFrame(capture);

That will not work with OpenCV 2.2, but if you use OpenCV 2.1 it will work fine !

Ammunition

Answer 12

If you are on windows platform, try DirectShow (IAMStreamConfig).

http://msdn.microsoft.com/en-us/library/dd319784%28v=vs.85%29.aspx

Mount

Answer 13

Just one information that could be valuable for people having difficulties to change the default capture resolution (640 x 480) ! I experimented myself a such problem with opencv 2.4.x and one Logitech camera ... and found one workaround !

The behaviour I detected is that the default format is setup as initial parameters when camera capture is started (cvCreateCameraCapture), and all request to change height or width :

cvSetCaptureProperty( capture, CV_CAP_PROP_FRAME_WIDTH, ... 

or

cvSetCaptureProperty( capture, CV_CAP_PROP_FRAME_HEIGHT, ...

are not possible afterwards ! Effectively, I discovered with adding return error of ioctl functions that V4l2 driver is returning EBUSY for thet requests ! Therefore, one workaround should be to change the default value directly in highgui/cap_v4l.cpp :

*#define DEFAULT_V4L_WIDTH  1280    // Originally 640* 

*#define DEFAULT_V4L_HEIGHT 720     // Originally 480*

After that, I just recompiled opencv ... and arrived to get 1280 x 720 without any problem ! Of course, a better fix should be to stop the acquisition, change the parameters, and restart stream after, but I'm not enough familiar with opencv for doing that !

Hope it will help.

Michel BEGEY

Cockcroft

Answer 14

Try this:

capture = cvCreateCameraCapture(-1);
//set resolution
cvSetCaptureProperty(capture, CV_CAP_PROP_FRAME_WIDTH, frameWidth);
cvSetCaptureProperty(capture, CV_CAP_PROP_FRAME_HEIGHT, frameHeight);

Slovak

So you suggest setting the initial parameter to -1, then? What does that achieve? – Masonmasonic

The initial parameter -1 for cvCreateCameraCapture will select the first available device/camera. – Larue

Answer 15

cvQueryFrame(capture);

cvSetCaptureProperty( capture, CV_CAP_PROP_FRAME_WIDTH, any_supported_size );

cvSetCaptureProperty( capture, CV_CAP_PROP_FRAME_HEIGHT, any_supported_size);

cvQueryFrame(capture);

should be just enough!

Ferule

Maybe you can try explaining more about your code. As you've answered a very old question, original asker may not come back, but may help others. – Creatural