Abstract: The invention relates to a display method for an image-generation means making it possible to protect a screen of a viewing device against freezing of the image, characterized in that the image-generation means continually and alternately displays during the operation of the said viewing device a first sub-image and a second sub-image the first sub-image comprising a warning message and the second sub-image being the negative image of the first sub-image, the frequency of the display being sufficiently high to hide the warning message and when the viewing device sustains a failure causing the freezing of the image, the image-generation means permanently displays the warning message according to the last sub-image displayed on the screen. The invention applies particularly to the aviation field and more generally to any field in which a frozen image failure of a screen is critical.

Abstract: To reduce phenomena of distortion in an image intensifier tube, it is planned to provide its input with a permanent test pattern. The image of the test pattern is then read in real time and a deduction is made therefrom of the correction to be made to an image transmitted and converted by this intensifier tube. To create a permanent test pattern, references are made on the intensifier tube, on its input window. As a variant, the references are produced by an auxiliary laser source that illuminates the cathode of the tube by the rear.

Abstract: Disclosed is an improvement in image converter tubes that convert the X-ray image given by their input screen into a visible image. Stray glimmer develops on the insulators inside these tubes and the disclosure makes it possible to eliminate this glimmer by the deposition, on the insulators, of a thin layer of a product such as diamond-like carbon having a low secondary electron emission rate. Metal oxides are also suitable for this purpose. Application to image intensifiers.