I'm trying to replace a color and colors near it in a bitmap.
threshold() seems to work but it seems to be that you have to specify the exact color "==" or all colors before or after the exact color "<" & ">" plus "<=" and ">=". I am hoping that the mask parameter will help me find a way to find a color and a dynamic range of colors before and after it to be replaced. What is its intended usage?
Per the comment below Example 1 and 2:
bit.threshold(bit, bit.rect, point, ">", 0xff000000, 0xffff0000, 0x00FF0000);
bit.threshold(bit, bit.rect, point, ">", 0xff000000, 0xffff0000, 0x00EE0000);
If you're trying to do a flood fill, I don't think the mask parameter will help you. The mask parameter lets you ignore parts of the color in the test. In your case, you want to take into account all the channels of the color, you just want the matching to be fuzzy.
e.g. If you want to replace all pixels where the red component is 0, you can set mask to 0x00FF0000, so it will ignore the other channels.
The implementation pseudo-code probably looks something like this:
input = readPixel()
value = input & mask
if(value operation threshold)
{
writePixel(color)
}
Neither of your samples will produce anything because the mask limits the values to be between 0x00000000 and 0x00FF0000, then tests if they're greater than 0xFF000000.
I have also done this and eventually, I have found it best to create my own threshold-method. You can find it below. Everything is explained in comment.
//_snapshot is a bitmapData-object
for(var i:int = 0; i <= _snapshot.width; i++)
{
for(var j:int = 0; j <= _snapshot.height; j++)
{
//We get the color of the current pixel.
var _color:uint = _snapshot.getPixel(i, j);
//If the color of the selected pixel is between certain values set by the user,
//set the filtered pixel data to green.
//Threshold is a number (can be quite high, up to 50000) to look for adjacent colors in the colorspace.
//_colorToCompare is the color you want to look for.
if((_colorToCompare - (100 * _threshold)) <= _color && _color <= (_colorToCompare + (100 * _threshold)))
{
//This sets the pixel value.
_snapshot.setPixel(i, j, 0x00ff00);
}
else
{
//If the pixel color is not within the desired range, set it's value to black.
_snapshot.setPixel(i, j, 0x000000);
}
}
}
Related
This question already has a working answer at : Weird graphical bug in > AS3?
I'm trying to make a simple tile lighting system in AS3 and the problem I've come across is that I have no idea how to change the color based on distance using hexadecimal color codes
heres the code for the color changing part:
for (var i:int = 0; i < buttons.length; i++) {
lightFact = getDistance(lightSource, buttons[i])
colorTransform2.color = 0x000000
DisplayObject(buttons[i]).transform.colorTransform = colorTransform2;
}
lightFact being the distance from the lightSource, if you can't figure that out from the function name.
I'm not sure what the final objective is for this code but here we go.
getDistance() should return a numeric value. Next step is to create a function or algorithm that codify a number into a color. This could be just setting the R of the RGB color equals to the distance (setting a cap in 255) or many if-else statements like:
if(lightFact < XValue)
{
colorTransform2.color = 0xFF0000;
}
else if(lightFact < YValue)
{
colorTransform2.color = 0x00FF00;
}
else
{
colorTransform2.color = 0x0000FF;
}
or any other more complex codification you might like. Any codification you choose will, either way, need some kind of logic that checks lightFact's value and based on it (and any other variables you may have) makes a calculation or decision to set a different value to colorTransform2.color. Otherwise colorTransform.color will always be 0x000000 (black/turned off).
Can you check how similar a code is to another colour, If e.g. 0xFFFFFF is similar to 0xFBFBFB then change colour.
im not sure how the colour code works, so if you know a tip on the code, can you please share
A simple method to determinate proximity between colors, is to do so for each color component.
In AS3, a color is a number containing 3 components : red, green and blue (There's sometimes a fourth component for transparency - alpha)
Each component is contained in 1 byte, for a value of 0 to 255. (0x00 to 0xFF)
Here is a way to get each color component from the color itself :
var red:int = (color & 0xFF0000) >>> 16;
var green:int = (color & 0xFF00) >>> 8;
var blue:int = color & 0xFF;
Once you have the color components of each color, you can compare them 2 by 2, and combine the results:
var red_proximity = Math.abs(red1 - red2);
var green_proximity = Math.abs(green1 - green2);
var blue_proximity = Math.abs(blue1 - blue2);
var color_proximity = red_proximity + green_proximity + blue_proximity;
The result will be a number between 0 and 765; 0 meaning the color are exactly the same, and 765 meaning that they are completely differents.
(Note that I am using Math.abs() to ensure that the proximity values are always positive.)
The last step now is to choose a threshold value to determine if the colors are "too close". The chosen value is usually arbitrary, so test a few and take your pick. For the example, I'm using the value '84'.
if (color_proximity < 84) {
// color is too close : change it
} else {
// color is okay : do nothing ?
}
This is only one method, and if you have to play a lot with colors, search a bit on the web for other algorithm; It's always usefull.
is there any way to choose an area on the canvas by color and clip it?
I want to be able to clip an undefined aread that the only thing in common between all the pixels is that they all have the same color.
thanks
Live Demo
Below is a way to select a color.. and do whatever you want with it. I pass a color I want to find iterate over every pixel and remove the color that matches, since Im not sure what you meant by clipping I assumed you mean remove. However please note on large images this method will be slow.
// Takes an array with 3 color components, rgb
function removeColor(color){
var canvasData = ctx.getImageData(0, 0, 256, 256),
pix = canvasData.data;
for (var i = 0, n = pix.length; i <n; i += 4) {
if(pix[i] === color[0] && pix[i+1] === color[1] && pix[i+2] === color[2]){
pix[i+3] = 0;
}
}
ctx.putImageData(canvasData, 0, 0);
}
removeColor([0,0,255]); // Removes blue.
And like Simon pointed out the code above will get the exact color. Below will grab the approximate color, which is good if you have colors overlapping or very close to each other.
Demo 2 with approximation
I want to insert a pixel with a color, and I use this code:
context.fillStyle='RGB('+s[i]+')';
context.fillRect(i,y,1,1)
Is there a shorter way to do it? e.g. in a single line of code?
My main goal is to reduce the amount of code.
There really isn't a shorter way to do it besides the method you used above. You don't have to include a fillStyle every time so it essentially is only one line of code to fill a pixel.
Like Petteri pointed out there is another way to fill pixels, it involves manipulating the pixel data directly.
Live Demo
var canvasData = ctx.getImageData(0,0,canvasWidth,canvasHeight);
//color 100,100 red
canvasData.data[((100*(canvasData.width*4)) + (100*4)) + 0] = 255;
ctx.putImageData(canvasData,0,0);
also note with the above method you would need to repeat that line 3 times once for each component of the color. For example to set red, green, blue, and the alpha you would use
canvasData.data[((100*(canvasData.width*4)) + (100*4)) + 0] //red
canvasData.data[((100*(canvasData.width*4)) + (100*4)) + 1] //green
canvasData.data[((100*(canvasData.width*4)) + (100*4)) + 2] //blue
canvasData.data[((100*(canvasData.width*4)) + (100*4)) + 3] //alpha
granted you could have your data in an array, and just loop through that and color as needed.
You can edit the image data of the canvas directly. Here is a good example how to do it: http://beej.us/blog/2010/02/html5s-canvas-part-ii-pixel-manipulation/
No, there is no single line of code way to change a single pixel to one color. Well, there sort-of is.
As Petteri noted, there is a way to change each pixel directly, which will probably accomplish what you want. I assume what you want is to change one pixel to one color, and the next pixel to another color, etc.
For instance here is a function for desaturating a canvas. What it does is takes every pixel and averages the RGB values to be color-neutral (have no saturation). The result is a grayscale image.
function grayscale() {
var imageData = ctx.getImageData(0,0,can.width, can.height);
var pixels = imageData.data;
var numPixels = pixels.length;
ctx.clearRect(0, 0, can.width, can.height);
for (var i = 0; i < numPixels; i++) {
var average = (pixels[i*4] + pixels[i*4+1] + pixels[i*4+2]) /3;
// set red green and blue pixels to the average value
pixels[i*4] = average;
pixels[i*4+1] = average;
pixels[i*4+2] = average;
}
ctx.putImageData(imageData, 0, 0);
}
As you can see it is iterating over each pixel. It could be easily mofied to have each pixel changed as a one-liner.
Instead of:
pixels[i*4] = average;
pixels[i*4+1] = average;
pixels[i*4+2] = average;
You'd write:
// Take out 3 values starting at i*4 and add the new RGB for that pixel
pixels.splice(i*4,3,REDVALUE,GREENVALUE,BLUEVALUE);
Which would accomplish what you'd want. It's not the most efficient way under the sun, but it would accomplish your goal :)
fillStyle="rgb("+a[m];
fillRect(m,o,1,1);
Someone did with that :P
I have a whole bunch of jpg files that I need to use in a project, that for one reason or another cannot be altered. Each file is similar (handwriting), black pen on white BG. However I need to use these assets against a non-white background in my flash project, so I'm trying to do some client-side processing to get rid of the backgrounds using getPixel and setPixel32.
The code I am currently using currently uses a linear comparison, and while it works, the results are less than expected, as the shades of grey are getting lost in the mix. Moreso than just tweaking my parameters to get things looking proper, I get the feeling that my method for computing the RGBa value is weak.
Can anyone recommend a better solution than what I'm using below? Much appreciated!
private function transparify(data:BitmapData) : Bitmap {
// Create a new BitmapData with transparency to return
var newData:BitmapData = new BitmapData(data.width, data.height, true);
var orig_color:uint;
var alpha:Number;
var percent:Number;
// Iterate through each pixel using nested for loop
for(var x:int = 0; x < data.width; x++){
for (var y:int = 0; y < data.height; y++){
orig_color = data.getPixel(x,y);
// percent is the opacity percentage, white should be 0,
// black would be 1, greys somewhere in the middle
percent = (0xFFFFFF - orig_color)/0xFFFFFF;
// To get the alpha value, I multiply 256 possible values by
// my percentage, which gets multiplied by 0xFFFFFF to fit in the right
// value for the alpha channel
alpha = Math.round(( percent )*256)*0xFFFFFF;
// Adding the alpha value to the original color should give me the same
// color with an alpha channel added
var newCol = orig_color+alpha;
newData.setPixel32(x,y,newCol);
}
}
var newImg:Bitmap = new Bitmap(newData);
return newImg;
}
Since it's a white background, blendMode may give you a better result.