Convert DICOM to PNG
JPG compression introduces artifacts — blocky distortions near high-contrast edges — that are acceptable for photographs but undesirable for medical images where fine detail matters. PNG uses lossless compression: the output pixel values are byte-identical to the input, with no generation loss regardless of how many times the file is opened and resaved.
For personal use (sharing with a doctor, attaching to an insurance claim) JPG at high quality is fine and produces smaller files. For legal exhibits, publication, or any case where image quality may be questioned, PNG is the safer choice — there is nothing to argue about regarding compression artifacts.
This converter supports both PNG and JPG output. Windowing is applied in the same way for both: DICOM tags are read, rescale and VOI windowing are applied, and the result is an 8-bit grayscale (or RGB for color modalities) image. Only the output encoding differs.
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Questions
Is PNG better than JPG for medical images?
PNG is lossless — no information is discarded during compression. For most practical sharing purposes (email, PDF embedding) a high-quality JPG at 92% quality is indistinguishable. For archival use or when image quality may be scrutinized, PNG avoids the question.
Why is my PNG so large?
PNG is lossless, so file sizes for medical images — which tend to have high bit depth and fine gradients — can be large. A typical CT slice might be 200-500 KB as a high-quality JPG and 2-4 MB as PNG. Use JPG unless lossless quality is specifically required.
Can I get 16-bit PNG output?
This converter outputs 8-bit after windowing, which is the correct display depth for most purposes. Raw 16-bit DICOM pixels (unwindowed) are rarely useful without a DICOM viewer, but 16-bit PNG export is a planned feature for research users.