The application of the Medipix-1 hybrid pixel detector device for direct non destructive observation of damage development in gradually stressed materials by means of X-ray transmission measurements (so called X-Ray Dynamic Defectoscopy or XRDD) has been recently successfully demonstrated. It was found that both the sensitivity and the spatial resolution of the XRDD method depend significantly on the stability of the detecting device and on the quality of the X-ray beam. This paper is a study of the imaging quality and the temperature dependent behaviour of the Medipix-1 device. In XRDD tests we observed that on the edge of a sample slit, where an extremely sharp contrast takes place, the slit image is expanded and broadened. Results of the study of contrast influence on the image quality are presented in this paper. The dependency of the electronic noise on the device temperature was measured with respect to the XRDD accuracy.