Techniques are disclosed for identifying and reducing pixel-specific image distortion of an x-ray detector. In one example, an x-ray detector obtains, for various calibration positions, two-dimensional (2D) images of a calibration object. The calibration object comprises reference points that comprise spatial characteristics. Processing circuitry computes an image distortion field across a plurality of pixels of the x-ray detector based on imaged characteristics of the reference points in each of the 2D images, the spatial characteristics of the reference points, and the calibration positions. The processing circuitry computes, based on the computed image distortion field, a correction transform for correcting image distortion across the x-ray detector. The processing circuitry applies the correction field to a preliminary image obtained by the x-ray detector to obtain a corrected image exhibiting reduced pixel-specific image distortion.