i take in an array CRgb tempArray[IMG_HEIGHT][IMG_WIDTH]; //CRgb is a class of 3 unsigned glubytes ::glReadPixels(0,0,m_iWidth ,m_iHeight,GL_RGB, GL_UNSIGNED_BYTE, tempArray); i do some calculations and draw it back to the screen but i get a diagonal line down the image from the bottom left corner to the top right. i only traverse the array and change some RGB values? ::glDrawPixels(m_iWidth, m_iHeight, GL_RGB, GL_UNSIGNED_BYTE, tempArray); has anyone had this problem before??