[Solved] Patterns in a random QImage?
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Hi, I have a basic QImage/QLabel question. I tried to fill an image with random values and display it on the screen. But for some reason, I can see very distinct repeated patterns. Is there something obvious that I am missing? Thanks!
@
srand(time(0));
QImage random(w,h,QImage::Format_RGB888);
random.fill(Qt::black);
for(int j=0; j<h; j++) {
for(int i=0; i<w; i++) {
if((rand()%2) == 0) {
random.setPixel(i, j, qRgb(255, 0, 0));
}
}
}
QLabel m_picture;
m_picture->setPixmap(QPixmap::fromImage(random));
m_picture->show();
@and it comes out looking like this:
!http://i.imgur.com/BrnY9.png(QImage Display)!
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maybe try this
@
QImage random(w,h,QImage::Format_RGB888);
random.fill(Qt::black);
for(int j=0; j<h; j++) {
for(int i=0; i<w; i++) {
srand(time(0));
if((rand()%2) == 0) {
random.setPixel(i, j, qRgb(255, 0, 0));
}
}
}
QLabel m_picture;
m_picture->setPixmap(QPixmap::fromImage(random));
m_picture->show();
@
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interestingly enough that does fix the problem, as does
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float r = (float)rand()/(float)RAND_MAX;
if(r<.5) {
random.setPixel(i, j, qRgb(255, 0, 0));
}
@I guess this is one way to visualize the weakness of the c standard psuedorandom number generator in the ones digit.
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rand() was always a week function in C...
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