This allocates space in the ofImage, both the ofPixels and the ofTexture that the ofImage contains.

img.allocate(640, 480, OF_IMAGE_COLOR);
int i = 0;
while ( i < img.getPixels().size() ) {
    img.getPixels()[i] = abs(sin( float(i) / 18.f)) * 255.f; // make some op-art
    i++;
}
img.update();

It allocates an image of width (w) and height (h). The type can be of three types: OF_IMAGE_GRAYSCALE, OF_IMAGE_COLOR, OF_IMAGE_COLOR_ALPHA. You don't need to call this before loading an image, but for when you want to allocate space ahead of when you are going to use the image.

This binds the ofTexture instance that the ofImage contains so that it can be used for advanced drawing

void ofApp::setup() {
    img.allocate(256, 256, OF_IMAGE_COLOR);
    int i = 0;
    while ( i < img.getPixels().size() ) {
        img.getPixels()[i] = abs(sin( float(i) / 18.f )) * 255.f;
        i++;
    }
    img.update();

    mesh.setMode(OF_PRIMITIVE_TRIANGLE_STRIP);

    mesh.addVertex(ofVec2f(10, 10));
    mesh.addVertex(ofVec2f(410, 10));
    mesh.addVertex(ofVec2f(410, 410));
    mesh.addVertex(ofVec2f(10, 410));
    mesh.addVertex(ofVec2f(10, 10));

    mesh.addTexCoord(ofVec2f(0, 0));
    mesh.addTexCoord(ofVec2f(256, 0));
    mesh.addTexCoord(ofVec2f(256, 256));
    mesh.addTexCoord(ofVec2f(0, 256));
    mesh.addTexCoord(ofVec2f(0, 0));
}
void ofApp::draw(){

    ofBackground(255, 255, 255); // background white

    img.bind();
    mesh.draw();
    img.unbind();
}

This clears the texture and pixels contained within the ofImage.

This crops the image to the w,h passed in from the x,y position.

Draws the ofImage into the x,y location using the default height and width of the image.

Draws the ofImage into the x,y location and with the width and height, with any attendant scaling that may occur from fitting the ofImage into the width and height.

Draws the ofImage into the x,y,z location with the default height and width. You should ensure that you turn on depth sorting using glEnable(GL_DEPTH) before trying to draw multiple objects into z-space.

Draws the ofImage into the x,y,z location and with the width and height, with any attendant scaling that may occur from fitting the ofImage into the width and height. You should ensure that you turn on depth sorting using glEnable(GL_DEPTH) before trying to draw multiple objects into z-space.

Draws a subsection of the image (functions like a clipping mask) without altering any pixel data. (x,y) are the position to draw the cropped image at, (w,h) is the size of the subsection to draw and the size to crop (these can be different using the function below with sw,sh) and (sx,sy) are the source pixel positions in the image to begin cropping from.

// crop the image from the mouse position to 100x100 pixels and draw it at 0,0
img.drawSubsection(0, 0, 100, 100, mouseX, mouseY);

An example showing how to use drawSubsection can be found in of_release

(sw,sh) indicate the source width and height of the cropped area and the (w,h) indicate the size to draw the cropped area at.

Returns the height of the image in pixels.

Returns the width of the image in pixels.

Grabs pixels from the opengl window specified by the region (x, y, w, h) and turns them into an image. It resizes or allocates the ofImage if it's necessary.

Returns whether the image has been allocated either by a call to allocate or by loading pixel data into the image.

Returns whether the ofImage has a texture or not. If not, nothing will be drawn to the screen if the draw() method is called.

This reflects the pixels of the image across the vertical and/or horizontal axis.

This creates an ofImage from a file which can be a local string or a URL, allocating space for the pixels, and copying the pixels into the texture that the ofImage instance contains.

ofImage img("http://www.openframeworks.cc/wp-content/themes/ofw/images/ofw-logo.gif");

or

ofImage img("anImage.png"); // assumes this is in bin/data

This creates an ofImage but doesn't allocate any memory for it, so you can't use the image immediately after creating it.

This removes any anchor positioning, meaning that the ofImage will be draw with the upper left hand corner at the point passed into draw().

Resizes the image to a new size (w, h); Can be used to scale up or down an image.

Rotates the image by a multiple of 90 degrees, for instance, if you pass in 2, then the image will be rotated 180 degrees.

Changes the drawing position specified by draw() from the normal top-left corner of the image to a position specified by xPct and yPct in relation to the dimensions of the image. This can be useful for aligning and centering images as well as rotating an image around its center.

Note: range of xPct and yPct is 0.0 to 1.0. For xPct, 1.0 represents the width of the image. For yPct, 1.0 represents the height of the image. These values are not capped.

For example to draw an image so that its center is at 100, 100:

myImage.setAnchorPercent(0.5, 0.5);
myImage.draw(100, 100);

To rotate an image around its center at 100, 100:

ofPushMatrix();
  ofTranslate(100, 100, 0);
  ofRotate(45);
  myImage.setAnchorPercent(0.5, 0.5);
  myImage.draw(0, 0);
ofPopMatrix();

To align the right side of an image with the right edge of the window:

myImage.setAnchorPercent(1.0, 0.0);
myImage.draw(ofGetWidth(), 0);

Changes the drawing position specified by draw() from the normal top-left corner of the image to a position specified by x and y, measured in pixels. This can be useful for aligning and centering images as well as rotating an image around its center.

Note: see also setAnchorPercent() if you want to specify the anchor as a percentage of the image size.

For example to draw an image so that its center is at 100, 100:

myImage.setAnchorPoint(myImage.getWidth()/2, myImage.getHeight()/2);
myImage.draw(100, 100);

To rotate an image around its center at 100, 100:

ofPushMatrix();
  ofTranslate(100, 100, 0);
  ofRotate(45);
  myImage.setAnchorPoint(myImage.getWidth()/2, myImage.getHeight()/2);
  myImage.draw(0, 0);
ofPopMatrix();

To align the right side of an image with the right edge of the window:

myImage.setAnchorPoint(myImage.getWidth(), 0.0);
myImage.draw(ofGetWidth(), 0);

This sets the compression level used when creating mipmaps for the ofTexture contained by the ofImage. This is quite different than the ofImageQualityType image quality parameter used in saveImage(). The different texture compression levels are: OF_COMPRESS_NONE, OF_COMPRESS_SRGB, OF_COMPRESS_ARB

Set the pixels of the image from an array of values, for an ofFloatImage these need to be floats, for an ofImage these need to be unsigned chars. The w and h values are important so that the correct dimensions are set in the image. This assumes that you're setting the pixels from 0,0 or the upper left hand corner of the image. The bOrderIsRGB flag allows you pass in pixel data that is BGR by setting bOrderIsRGB=false.

Copies in the pixel data from the 'pixels' array. Specify the corresponding width and height of the image you are passing in with 'w' and 'h'. The image type can be OF_IMAGE_GRAYSCALE, OF_IMAGE_COLOR, or OF_IMAGE_COLOR_ALPHA.

Note: that your array has to be at least as big as [ width * height * bytes per pixel ].

If you have a grayscale image, you will have (widthheight) number of pixels. Color images will have (widthheight3) number of pixels (interlaced R,G,B), and coloralpha images will have (widthheight*4) number of pixels (interlaced R,G,B,A).

Note: You do not need to call allocate() before calling setFromPixels() as setFromPixels() re-allocates itself if needed.

Set the type of image to one of the following: OF_IMAGE_GRAYSCALE, OF_IMAGE_COLOR, OF_IMAGE_COLOR_ALPHA. This does cause the image to be reallocated and the texture to be updated, so it can be an expensive operation if done frequently. Converting down, for example from color to grayscale, loses information and is a destructive change.

For example, you can load in a color image, and convert it to grayscale:

myImage.loadImage("somethingColor.jpg");
myImage.setImageType(OF_IMAGE_GRAYSCALE);   // now I am grayscale;

If you set the ofImage to not use a texture it will contain the pixels of the image but cannot be drawn to the screen without copying its data into an ofTexture instance.

This turns on or off the allocation and use of a texture. any time you change the image (loading, resizing, converting the type), ofImage will upload data to an opengl texture. It may not be necessary, though, and it could be that you need to save memory on the graphics card, or that you don't need to draw this image on the screen. You can call this even before you load an image in to OF:

myImage.setUseTexture(false);
myImage.loadImage("blah.gif");

Since in the majority of cases, ofImages will be loaded in and drawn onscreen, the default is set to use a texture.

This unbinds the ofTexture instance that the ofImage contains. Call this after you call bind().

This method should be called after you update the pixels of the image and want to ensure that the changes to the pixels are reflected in the ofTexture of the image. Many of the ofImage methods call this after they change the pixels, but if you directly manipulate the pixels of the ofImage, then you should make sure to call update() before trying to draw the texture of the image to the screen.