Method for estimating the quality of images compressed with a transformation based compression method, which is derived on the basis of estimated errors generated by quantization to obtain an image quality indicator and which requires no reference image, the transformation based compression method comprising the following steps: - transformation of the image data available in the two-dimensional discrete spatial domain into the two-dimensional discrete frequency domain by a transformation function resulting in at least one transformation block comprising at least one transformation coefficient, each transformation block of the same size consisting of transformation coefficients representing the same two-dimensional frequencies; - scaling of the resulting transformation coefficients; - quantization of the scaled transformation coefficients using a quantization parameter to set the number and/or size of quantization steps; the method for estimating the quality of images being carried out by a device and comprising the following steps: - calculation of a probability of each quantized transformation coefficient, representing one identical two-dimensional frequency, to be quantized to one certain quantized transformation coefficient value; - estimation of an identifying parameter of a probability density function of the non-quantized coefficient values, using the calculated probability for each quantized transformation coefficient, representing said one identical two-dimensional frequency, to be quantized to the certain quantized transformation coefficient value and a preset type of probability density function; - calculation of an image quality indicator from the summed estimated errors of each quantized transformation coefficient, whereby the estimated error for each quantized transformation coefficient is derived from the estimated identifying parameter of the corresponding probability density function and the quantization parameter, and wherein the image quality indicator is a peak signal to noise ratio of the image. - transformation of the image data available in the two-dimensional discrete spatial domain into the two-dimensional discrete frequency domain by a transformation function resulting in at least one transformation block comprising at least one transformation coefficient, each transformation block of the same size consisting of transformation coefficients representing the same two-dimensional frequencies; - scaling of the resulting transformation coefficients; - quantization of the scaled transformation coefficients using a quantization parameter to set the number and/or size of quantization steps; - calculation of a probability of each quantized transformation coefficient, representing one identical two-dimensional frequency, to be quantized to one certain quantized transformation coefficient value; - estimation of an identifying parameter of a probability density function of the non-quantized coefficient values, using the calculated probability for each quantized transformation coefficient, representing said one identical two-dimensional frequency, to be quantized to the certain quantized transformation coefficient value and a preset type of probability density function; - calculation of an image quality indicator from the summed estimated errors of each quantized transformation coefficient, whereby the estimated error for each quantized transformation coefficient is derived from the estimated identifying parameter of the corresponding probability density function and the quantization parameter, and