I am trying to rotate Qpixmap with Qtransformed, it seems the point of rotation is center of pixmap by default, how can i define custom point for example top mid of pixmap?
def rotate_pixmap(self):
pixmap = QtGui.QPixmap("image.png")
self.rotation += 1
transform = QtGui.QTransform().rotate(self.rotation)
pixmap = pixmap.transformed(transform, QtCore.Qt.SmoothTransformation)
self.label.setPixmap(pixmap)
Related
I use the following numpy array that hold an image which is black and white image with the following shape
print(img.shape)
(28, 112)
when I try to grayscale the image, to use it to get contours using opencv with following steps
#grayscale the image
grayed = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
#thredshold image
thresh = cv2.threshold(grayed, 0, 255, cv2.THRESH_BINARY_INV | cv2.THRESH_OTSU)[1]
I got the following error
<ipython-input-178-7ebff17d1c18> in get_digits(img)
6
7 #grayscale the image
----> 8 grayed = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
9
10
error: C:\projects\opencv-python\opencv\modules\imgproc\src\color.cpp:11073: error: (-215) depth == 0 || depth == 2 || depth == 5 in function cv::cvtColor
the opencv errors have no information in it to be able to get what is wrong
Here is the working code for how you were trying it:
img = np.stack((img,) * 3,-1)
img = img.astype(np.uint8)
grayed = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
thresh = cv2.threshold(grayed, 0, 255, cv2.THRESH_BINARY_INV | cv2.THRESH_OTSU)[1]
A simpler way of getting the same result is to invert the image yourself:
img = (255-img)
thresh = cv2.threshold(img, 0, 255, cv2.THRESH_OTSU)[1]
As you discovered, as you perform different operations on images, the image is required to be in different formats.
cv2.THRESH_BINARY_INV and cv2.THRESH_BINARY are designed to take a color image (and convert it to grayscale) so you need a three channel representation.
cv2.THRESH_OTSU works with grayscale images so one channel is okay for that.
Since your image was already grayscale from the start, you weren't able to convert it from color to grayscale nor did you really need to. I assume you were trying to invert the image but that's easy enough on your own (255-img).
At one point you tried to do an cv2.THRESH_OTSU with floating point values but cv2.THRESH_OTSU requires integers between 0 and 255.
If openCV had more user-friendly error messages it would really help with issues like these.
I am trying to catch resize event of the window, and when I do, basically delete all the widget items in a gridLayout and rebuild the rows/columns to fit the new resized window. I am having trouble getting this to work properly and not sure if this is the best method that I have used. Right now two issues happen:
It doesn't seem to be deleting items, rebuilding and adding the columns properly as I resize the window bigger (some items delete, some get added, but seem to just overlap and never fit to the new window size).
Resize seems to get called on start/creation of the window.
class Window (QtGui.QMainWindow):
def __init__(self):
super(Window, self).__init__()
self.thumbs = []
self.thumbWidgets = []
self._resize_timer = None
self.resizeCompleted.connect(self.handleResizeCompleted)
self.setGeometry(100, 100, 800, 600)
self.home()
def home(self):
self.centralwidget = QtGui.QWidget(self)
'''MainLAYOUT
'''
self.mainLayout = QtGui.QVBoxLayout(self.centralwidget)
self.thumb_tab_QGroupBox = QtGui.QGroupBox(self.centralwidget)
'''GroupBoxLAYOUT
'''
self.vLayout = QtGui.QVBoxLayout(self.thumb_tab_QGroupBox)
self.vLayout.setObjectName("GroupVLayout")
#Scroll Area
self.thumbScrollArea = QtGui.QScrollArea(self.thumb_tab_QGroupBox)
self.thumbScrollArea.setVerticalScrollBarPolicy(QtCore.Qt.ScrollBarAlwaysOn)
self.thumbScrollArea.setHorizontalScrollBarPolicy(QtCore.Qt.ScrollBarAlwaysOn)
self.thumbScrollArea.setWidgetResizable(True)
self.thumbScrollArea.setAlignment(QtCore.Qt.AlignLeft)
self.thumbScrollArea.setObjectName("thumb_scrollArea")
self.scrollAreaWidgetContents = QtGui.QWidget()
self.scrollAreaWidgetContents.setMinimumSize(QtCore.QSize(840, scrollAreaX))
self.scrollAreaWidgetContents.setObjectName("scrollAreaWidgetContents")
self.thumbScrollArea.setWidget(self.scrollAreaWidgetContents)
self.vLayout.addWidget(self.thumbScrollArea)
self.mainLayout.addWidget(self.thumb_tab_QGroupBox)
#Grid in Scroll Area
self.gridLayoutWidget = QtGui.QWidget(self.scrollAreaWidgetContents)
self.gridLayoutWidget.setObjectName("gridLayoutWidget")
self.gridLayout_QGridLayout = QtGui.QGridLayout(self.gridLayoutWidget)
self.gridLayout_QGridLayout.setObjectName("gridLayout")
#Loads thumbnails
self.getThumbnails()
self.mainLayout.setAlignment(QtCore.Qt.AlignLeft)
self.setCentralWidget(self.centralwidget)
def resizeEvent(self, resizeEvent):
self.updateResizeTimer(300)
def updateResizeTimer(self, interval=None):
if self._resize_timer is not None:
self.killTimer(self._resize_timer)
if interval is not None:
self._resize_timer = self.startTimer(interval)
else:
self._resize_timer = None
def timerEvent(self, event):
if event.timerId() == self._resize_timer:
self.updateResizeTimer()
self.resizeCompleted.emit()
def handleResizeCompleted(self):
print('resize complete')
# Get new window size on resize
width = self.centralwidget.frameGeometry().width()
height = self.centralwidget.frameGeometry().height()
thumbsPerRow = width / 200
print "numThumbnails per Width", thumbsPerRow
self.gridLayoutWidget.adjustSize()
self.gridLayout_QGridLayout.maximumSize()
for widget in self.thumbWidgets:
print "Removing widget", widget
self.gridLayout_QGridLayout.removeWidget(widget)
#widget.deleteLater()
self.populate(self.thumbWidgets, QtCore.QSize(200,200), thumbsPerRow)
def queryThumbnailCount(self):
....
...
..
return sizeX
def getThumbnails(self):
.....
....
...
.
self.createThumbWidgets(self.thumbs, QtCore.QSize(200,200))
self.populate(self.thumbs, QtCore.QSize(200,200))
def createThumbWidgets(self, pics, size, imagesPerRow=4, flags=QtCore.Qt.KeepAspectRatioByExpanding):
for pic in pics:
label = QtGui.QLabel("")
pixmap = QtGui.QPixmap(pic)
pixmap = pixmap.scaled(size, flags)
label.setPixmap(pixmap)
self.thumbWidgets.append(label)
#Add thumbnails to grid
def populate(self, pics, size, imagesPerRow=6, flags=QtCore.Qt.KeepAspectRatioByExpanding):
row = col = 0
for widget in self.thumbWidgets:
print "Adding Image to column "+str(col)
self.gridLayout_QGridLayout.addWidget(widget, row, col)
col +=1
if col % imagesPerRow == 0:
row += 1
col = 0
GUI = Window()
GUI.show()
This might be better achieved with a QGraphicsView.
Create a subclass of a QGraphicsView that also creates a QGraphicsScene for itself. Have it store the list of pixmaps you want it to display. Override the resizeEvent in your subclass and have it clear the QGraphicsScene and re-add all the pixmaps to the scene using QGraphicsPixmapItems. Before you add them to the scene, get the total width and height from the QGraphicsView.viewport(). You can get the individual pixmap width/height by dividing by rows/columns. Then scale each pixmap before you add it to the scene.
I have a problem with the rotation within a JSVGCanvas.
The user can load SVG images into a document page (JLayeredPane).
Every image displays in his own JSVGCanvas and has his own class.
The user can resize the image by dragging the endpoints and also move the image around.
The rotation works perfectly
(Basic and rotated situation)
Only the subsequent change of the bounding box of the Canvas results in a scaling, which no longer corresponds to the original size
(Finally after setting Boundingbox)
Code fragment in UpdateManager():
....
// calculating new canvas bounding box
AffineTransform at = AffineTransform.getRotateInstance(rotation*Math.PI/180.0,
originalX + originalW/2.0,
originalY + originalH/2.0);
Rectangle2D.Double rect = new Rectangle2D.Double(originalX, originalY, originalW, originalH);
Shape s = at.createTransformedShape(rect);
xx = s.getBounds2D().getX();
yy = s.getBounds2D().getY();
ww = s.getBounds2D().getWidth();
hh = s.getBounds2D().getHeight();
canvas.setRenderingTransform(AffineTransform.getRotateInstance(rotation*Math.PI/180.0,
originalW/2.0, originalH/2.0));
// this.setBounds() will do the stuff and also change the Canvas Bounds
setBounds(xx, yy, ww, hh);
....
I am grateful for any help.
Solved...
I have found the way to solve this problem:
....
// calculating new canvas bounding box
AffineTransform at = AffineTransform.getRotateInstance(rotation*Math.PI/180.0,
originalX + originalW/2.0,
originalY + originalH/2.0);
Rectangle2D.Double rect = new Rectangle2D.Double(originalX, originalY, originalW, originalH);
Shape s = at.createTransformedShape(rect);
xx = s.getBounds2D().getX();
yy = s.getBounds2D().getY();
ww = s.getBounds2D().getWidth();
hh = s.getBounds2D().getHeight();
double rotScale = originalW/ww;
double diffX = (originalW * rotScale - originalW) / 2.0 * -1.0;
double diffY = (originalH * rotScale - originalH) / 2.0 * -1.0;
AffineTransform af = AffineTransform.getScaleInstance(rotScale, rotScale);
af.preConcatenate(AffineTransform.getTranslateInstance(diffX, diffY));
af.preConcatenate(AffineTransform.getRotateInstance(rotation*Math.PI/180.0, originalW/2.0, originalH/2.0));
canvas.setRenderingTransform(af);
// this.setBounds() will do the stuff and also change the Canvas Bounds
setBounds(xx, yy, ww, hh);
....
Maybe this will help others having the same problem.
Picture solved
every one.
I'm a android developer.
I want to scale my image from center of displayed part of image with matrix.
So, I scaled my image with matrix. And then moved it with the calculated pointer.
But, the Application not work correctly.
This can't find the correct center, so when it does, it moved right.
Why this is?
I can't find the problem.
The code followed.
matrix.reset();
curScale += 0.02f;
orgImage.getHeight();
w = orgImage.getWidth();
matrix.postScale(curScale, curScale);
rtnBitmap = Bitmap.createBitmap(orgImage, 0, 0, w, h, matrix, true);
curImageView.setImageBitmap(rtnBitmap);
Matrix curZoomOutMatrix = new Matrix();
pointerx =(int ) ((mDisplayWidth/2 - curPosX) * curScale);
curPosX = - pointerx;
pointery =(int ) ((mDisplayWidth/2 - curPosY) * curScale);
curPosY = - pointery;
Log.i("ZoomOut-> posX = ", Integer.toString(curPosX));
Log.i("ZoomOut-> posY = ", Integer.toString(curPosY));
curZoomOutMatrix.postTranslate(curPosX, curPosY);
curImageView.setImageMatrix(curZoomOutMatrix);
curImageView.invalidate();
Did you have any sample code for center zoomIn and zoomOut the imageView with matrix?
Who can explain for that?
Please help me.
Or, It's my fault.
First, I scale the image from original one.
So, The image is (width, height) * scale;
Then I calculate the absolute position of the point that is displayed center. And then, move my ImageView to the calculated position from which the view is. My fault are here.
When i calculate view position, I change the position from now scale.
So, when it scaled, the position is not <original position> * <now scale>. It was <original position * <scale> * <now scale>, the result was strange position.
So i remade add to calculate the center position from original one.
That mode is now following.
public void calculate(float offset) {
float tmpScale = curScale - offset;
float orgWidth = (mDisplayWidth / 2 - curPosX) / tmpScale;
float orgHeight = (mDisplayHeight / 2 - curPosY) / tmpScale;
int tmpPosX = (int)(mDisplayWidth / 2 - orgWidth * curScale);
int tmpPosY = (int)(mDisplayHeight / 2 - orgHeight * curScale);
curPosX = tmpPosX;
curPosY = tmpPosY;
Matrix matrix = new Matrix();
matrix.postTranslate(tmpPosX, tmpPosY);
curImageView.setImageMatrix(matrix);
curImageView.invalidate();
}
Thank you. every one.
uniform sampler2D sampler0;
uniform vec2 tc_offset[9];
void blur()
{
vec4 sample[9];
for(int i = 0; i < 9; ++i)
sample[i] = texture2D(sampler0, gl_TexCoord[0].st + tc_offset[i]);
gl_FragColor = (sample[0] + (2.0 * sample[1]) + sample[2] +
(2.0 * sample[3]) + sample[4] + 2.0 * sample[5] +
sample[6] + 2.0 * sample[7] + sample[8] ) / 13.0;
}
How does the sample[i] = texture2D(sample0, ...) line work?
It seems like to blur an image, I have to first generate the image, yet here, I'm somehow trying to query the very iamge I'm generating. How does this work?
It applies a blur kernel to the image. tc_offset needs to be properly initialized by the application to form a 3x3 area of sampling points around the actual texture coordinate:
0 0 0
0 x 0
0 0 0
(assuming x is the original coordinate). The offset for the upper-left sampling point would be -1/width,-1/height. The offset for the center point needs to be carefully aligned to texel center (the off-by-0.5 problem). Also, the hardware bilinear filter can be used to cheaply increase the amount of blur (by sampling between texels).
The rest of the shader scales the samples by their distance. Usually, this is precomputed as well:
for(int i = 0; i < NUM_SAMPLES; ++i) {
result += texture2D(sampler,texcoord+offsetscaling[i].xy)*offsetscaling[i].z;
}
One way is to generate your original image to render to a texture, not to the screen.
And then you draw a full screen quad using this shader and the texture as it's input to post-process the image.
As you note, in order to make a blurred image, you first need to make an image, and then blur it. This shader does (just) the second step, taking an image that was generated previously and blurring it. There needs to be additional code elsewhere to generate the original non-blurred image.