General Electric Company

Lawrence E Sieb

Barry F Belanger

David Gerard Mliner

For edge enhancement of a digitized fluorographic image, the original image is stored in a full frame memory. When each video vertical blanking pulse occurs time delays are initiated corresponding to shifting whole lines of pixels successively to the left and right and up and down by integral numbers before the pixels are read out of memory. As the pixels are read out for each vertical blanking cycle, they are multiplied by a coefficient related to the pixel shift number and the result is added to to image data from preceding cycles that are summed and stored in a second memory and the new result is returned to the second memory. The final result is an edge map in the second memory constituting digital values corresponding to the frequency components at edges. These are added to corresponding pixels in the original image, resulting in higher and sharper edges in a final digital image. The image is then converted to analog video signals to permit display on a video monitor.

Edge enhancement filtering for digital fluorography images

For hybrid digital subtraction angiography mask x-ray images are made at low and high x-ray tube anode kVp. Both exposures are terminated by AEC and the exposure times are calculated and stored and used to govern the times of a subsequent run sequence of alternate low and high energy pre-contrast and post-contrast exposure images. The data for the mask and subsequent images are stored individually on magnetic disk. A TV camera receives optical versions of the images. Its target is scanned or read out during a TV frame time between the end of a low energy exposure and the start of a high energy exposure. After the low energy mask exposure time is determined an anticipation or delay time is calculated and the low energy exposures in the run sequence are shifted from the vertical blank pulse preceding the frame in which the exposure starts by the delay time so all low energy exposures terminate coincident with the blanking pulse that precedes the read out frame. Since the high energy exposures are started at the end of the readout, minimum time between low and high exposures is achieved. High kVp is fixed. Low kVp and tube MA are selectable. High MA that the tube target can withstand thermally is calculated and adjusted so it will not result in excessive tube target bulk or focal spot temperature.

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Oconomowoc, WI, United States of America

Lawrence E Sieb