I am doing some operation where I need to replace the bigger rectangle with the smaller rectangle.
Most answers suggested to use smallerRectMat.copyTo(biggerRectMat) but it didn't give me the require output. The submat is changed but the original image is as it is.
And when I try to see the submat both became same of same smaller rectangle size.
Mat rectNose = testBuffer.submat(rectA.y,rectA.y+rectA.height,rectA.x,rectC.x+rectC.width);
Rect biggerRect = getHeadContour(testBuffer);
Mat rectHead = testBuffer.submat(biggerRect.y+1,biggerRect.y+biggerRect.height,biggerRect.x+1,biggerRect.x+biggerRect.width);
rectNose.copyTo(rectHead);
Imgcodecs.imwrite("/Users/test.jpg",rectHead);
Imgcodecs.imwrite("/Users/test1.jpg",rectNose);
Imgcodecs.imwrite("/Users/test1.jpg",testBuffer);
Basically I want to copy the rectangle near the nose region to the rectangle with blue boundary at forehead.
You can try ROI(Region Of Image) scaling
smallRect = img[rectA.y:rectA.y+rectA.height, rectA.x:rectC.x+rectC.width]
upscaledRegion = cv2.resize(smallRect , (biggerRect.width, biggerRect.height), interpolation=cv2.INTER_AREA)
img[biggerRect.y:biggerRect.y+biggerRect.height, biggerRect.x:biggerRect.x+biggerRect.width] = upscaledRegion
Related
Here is the picture I take with my USB camera. My camera has an angle with horizontal line, the target is on the bottom, with parallel and orthogonal lines delimiting rectangles. Post-it is a control marker of the center-rectangle.
Then I process several step-by-step processing in order to adjust the 'tilt' of the view and to extract lines.
Here is the line extraction without transform :
{"type":"toGray"} => mat.cvtColor( cv4.COLOR_BGR2GRAY);
{"type":"toBlur","size":10} => mat.gaussianBlur( new cv4.Size( size, size),0);
{"type":"toCanny","low":50,"high":150} => mat.canny( low_threshold, high_threshold);
{"type":"getLines","rho":1,"theta":0.017453292222222222,"threshold":15,"min_line_length":50,"max_line_gap":20 }] => let lines = mat.houghLinesP( rho, theta, threshold, min_line_length, max_line_gap);
Result is :
Now, I want to correct the tilt of view, using 'warpAffine' function, before extracting lines.
I select four points of the centered rectangle, in order to build two "three points array" (src, dst):
matTransf = cv4.getAffineTransform( srcPoints, dstPoints);
resultMat = mat.warpAffine( matTransf, new cv4.Size( mat.cols, mat.rows));
The result is the following:
Where is the mistake ?
I have tried too :
// four points at each corner of the rectangle, srcPoints for the picture, and dstPoints for the theoric shape
// With getPerspectiveTransform
matTransf = cv4.getPerspectiveTransform( srcPoints, dstPoints);
resultMat = mat.warpPerspective( matTransf, new cv4.Size( mat.cols, mat.rows));
// With findHomography
let result = cv4.findHomography( srcPoints, dstPoints);
matTransf = result.homography;
resultMat = mat.warpPerspective( matTransf, new cv4.Size( mat.cols, mat.rows));
Result is :
Best regards.
The transformation is not an affinity, it is a perspective described by a homography. Select in the image four corners of a physical rectangle, map them to points in a rectangle with the same aspect ratio as the physical one, estimate the homography from them (findHomography), finally warp (warpPerspective).
I have an image I want to partially mask (wallSprite), an image to act as a mask over it (wallMaskBox), and a node to hold both (wallCropNode). When I simply add both images as children of wallCropNode, both image display correctly:
var wallSprite = SKSpriteNode(imageNamed: "wall.png")
var wallCropNode = SKCropNode()
var wallMaskBox = SKSpriteNode(imageNamed: "blacksquaretiny.png")
wallMaskBox.zPosition = 100
wallCropNode.addChild(wallSprite)
wallCropNode.addChild(wallMaskBox)
gameplayContainerNode.addChild(wallCropNode)
But when I set the mask image as a maskNode property of the crop node:
var wallSprite = SKSpriteNode(imageNamed: "wall.png")
var wallCropNode = SKCropNode()
var wallMaskBox = SKSpriteNode(imageNamed: "blacksquaretiny.png")
wallMaskBox.zPosition = 100
wallCropNode.addChild(wallSprite)
wallCropNode.maskNode = wallMaskBox
gameplayContainerNode.addChild(wallCropNode)
the wallSprite image disappears entirely, instead of being partly cropped. Any ideas?
The issue is your black square image is completely opaque. Some (or all) of its pixels should be transparent (i.e., alpha = 0). The pixels that correspond to the mask node's transparent pixels will be masked out (i.e., not rendered) in the cropped node. To demonstrate this, I used your code to create the following.
Here's the original image:
Here's the mask image that I used for the maskNode. Note that the white regions are transparent (i.e., alpha = 0). From Apple's documentation,
When rendering its children, each pixel is verified against the
corresponding pixel in the mask. If the pixel in the mask has an alpha
value of less than 0.05, the image pixel is masked out. Any pixel not
rendered by the mask node is automatically masked out.
and here's the cropped node. I took a screenshot of the scene from the iPhone 6 simulator.
I rotated the image from the left to the image on the right using
image = cv2.warpAffine(image, R, dst_size, flags=cv2.INTER_LINEAR)
where dst_size is (547, 363), and I've modified R so that the original image should fit in the new dimensions.
I show the image with cv2.imshow('rect post-rotation', img) to show the image on the right. You can see that it appears clipped to a size of (363, 547), even though when I print out the img shape, I get (547, 363, 3).
Why does the shape of the image not reflect the shape of the displayed image?
you need to set the destination size to the rotated size ie:
cv::Size dst_size(imOrig.size().height,imOrig.size().width);
alternatively you can use transpose and flip for 90 degree rotation:
cv::Mat imRot90 = imOrig.t();
cv::flip(imRot90 ,imRot90 ,1);
cheers
in a school project i would like to do the following step to have a watermaked image in matlab
extract the edges from an image
insert a mark on this edge
reconstruct the image
extract the mark
could some one give me a link to have a good idea how to do it or help me to do that?
thank you in advance
You want to add a watermark to an image? Why not just overlay the whole thing.
if you have an image
img = imread('myimage.jpg')
wm = imread('watermark.jpg')
You can just resize the watermark to the size of the image
wm_rs = imresize(wm, [size(img,1) size(img,2)], 'lanczos2');
img_wm(wm_rs ~= 0) = wm_rs; %This sets non-black pixels to be the watermark. (You'll have to slightly modify this for color images)
If you want to put it on the edges of the image, you can extract them like this
edges = edge(rgb2gray(img),'canny')
Then you can set the pixels where the edges exist to be watermark pixels
img_wm = img;
img_wm(edges ~= 0) = wm_rs(edges~=0);
Instead of direct assignment you can play around with using a mix of the img and wm_rs pixel values if you want transparency.
You'll probably have to adjust some of what I said to color images, but most should be the same.
Here, is a nice and simple example how you can embed watermarks using MATLAB (in the spatial domain): http://imageprocessingblog.com/digital-watermarking/
see example below(R2017b or later release):
% your params
img = imread('printedtext.png');
Transparency = 0.6;
fontColor = [1,1,1]; % RGB,range [0,1]
position = [700,200];
%% add watermark
mask = zeros(size(img),'like',img);
outimg = insertText(mask,position,'china', ...
'BoxOpacity',0,...
'FontSize',200,...
'TextColor', 'white');
bwMask = imbinarize(rgb2gray(outimg));
finalImg = labeloverlay(img,bwMask,...
'Transparency',Transparency,...
'Colormap',fontColor);
imshow(finalImg)
Here's what I'm trying to do: On the left is a generic, uncolorized RGBA image that I've created off-screen and cached for speed (it's very slow to create initially, but very fast to colorize with any color later, as needed). It's a square image with a circular swirl. Inside the circle, the image has an alpha/opacity of 1. Outside the circle, it has an alpha/opacity of 0. I've displayed it here inside a UIView with a background color of [UIColor scrollViewTexturedBackgroundColor]. On the right is what happens when I attempt to colorize the image by filling a solid red rectangle over the top of it after setting CGContextSetBlendMode(context, kCGBlendModeColor).
That's not what I want, nor what I expected. Evidently, colorizing a completely transparent pixel (e.g., alpha value of 0) results in the full-on fill color for some strange reason, rather than remaining transparent as I would have expected.
What I want is actually this:
Now, in this particular case, I can set the clipping region to a circle, so that the area outside the circle remains untouched — and that's what I've done here as a workaround.
But in my app, I also need to be able to colorize arbitrary shapes where I don't know the clipping/outline path. One example is colorizing white text by overlaying a gradient. How is this done? I suspect there must be some way to do it efficiently — and generally, with no weird path/clipping tricks — using image masks... but I have yet to find a tutorial on this. Obviously it's possible because I've seen colored-gradient text in other games.
Incidentally, what I can't do is start with a gradient and clip/clear away parts I don't need — because (as shown in the example above) my uncolorized source images are, in general, grayscale rather than pure white. So I really need to start with the uncolorized image and then colorize it.
p.s. — kCGBlendModeMultiply also has the same flaws / shortcomings / idiosyncrasies when it comes to colorizing partially transparent images. Does anyone know why Apple decided to do it that way? It's as if the Quartz colorizing code treats RGBA(0,0,0,0) as RGBA(0,0,0,1), i.e., it completely ignores and destroys the alpha channel.
One approach that you can take that will work is to construct a mask from the original image and then invoke the CGContextClipToMask() method before rendering your image with the multiply blend mode set. Here is the CoreGraphics code that would set the mask before drawing the image to color.
CGContextRef context = [frameBuffer createBitmapContext];
CGRect bounds = CGRectMake( 0.0f, 0.0f, width, height );
CGContextClipToMask(context, bounds, maskImage.CGImage);
CGContextDrawImage(context, bounds, greyImage.CGImage);
The slightly more tricky part will be to take the original image and generate a maskImage. What you can do for that is write a loop that will examine each pixel and write either a black or white pixel as the mask value. If the original pixel in the image to color is completely transparent, then write a black pixel, otherwise write a white pixel. Note that the mask value will be a 24BPP image. Here is some code to give you the right idea.
uint32_t *inPixels = (uint32_t*) MEMORY_ADDR_OF_ORIGINAL_IMAGE;
uint32_t *maskPixels = malloc(numPixels * sizeof(uint32_t));
uint32_t *maskPixelsPtr = maskPixels;
for (int rowi = 0; rowi < height; rowi++) {
for (int coli = 0; coli < width; coli++) {
uint32_t inPixel = *inPixels++;
uint32_t inAlpha = (inPixel >> 24) & 0xFF;
uint32_t cval = 0;
if (inAlpha != 0) {
cval = 0xFF;
}
uint32_t outPixel = (0xFF << 24) | (cval << 16) | (cval << 8) | cval;
*maskPixelsPtr++ = outPixel;
}
}
You will of course need to fill in all the details and create the graphics contexts and so on. But the general idea is to simply create your own mask to filter out drawing of the red parts around the outside of the circle.