The Visible Human Image Data

The National Library of Medicine has undertaken to provide a set of digitized images of the human body for use in education and research. The Visible Human Project will initially create a digital image data set of a complete human male and female cadaver, with digitized anatomical photographs, as well as magnetic resonance imaging (MRI) and computer tomography (CT) data. The female data has just been made available (in December 1995) be we have not used it.

The Visible Man is a set of digital images of the body of a 39 year old man, Joseph Paul Jernigan, who donated his body to science after being convicted of murder and sentenced to death. He was executed by lethal injection in Texas in 1993.

Images of the body were first obtained using magnetic resonance imaging and X-ray computer tomography. It was then embedded in gelatin, frozen, and sliced crosswise into 1878 transverse slices, each 1 millimeter (mm) wide, with the surface of the body being photographed after every slice and digitized at a resolution of 1/3 mm, to give the anatomical data that is used here. Each slice of the original data is a 2048 x 1216 pixel 24-bit color image that is about 7.5 Mbytes uncompressed, with the entire data set being about 14 Gbytes.

We have cropped the original images and removed the gelatin background. The original data were transverse slices (axial view), and we have also constructed slices in two orthogonal planes (sagittal and coronal views). The resulting images were converted to JPEG format using a 75% quality value for the compression (note that JPEG uses lossy compression so the image quality is slightly reduced in the compression). This reduces the size of each axial image to between about 50 and 180 Kbytes, depending on the position of the slice. The sagittal images are slightly larger and the coronal images are much larger, from about 50 to 350 Kbytes.

We have also created lower resolution data for easier downloading. The medium resolution data has 2 times lower resolution for the axial images (i.e. 2/3 mm). For the the sagittal and coronal images, it uses data that is 3 times lower resolution in the horizontal directions and the same resolution in the vertical direction (i.e. 1 mm in each direction). The low resolution images are 2 times lower resolution than the medium resolution images (i.e. 2 mm in each direction for the sagittal and coronal images, 4/3 mm for the axial images).

Note that some sections of the data, in particular transverse sections of the chest, upper thigh and calf, are missing or corrupted due to problems in the initial data collection process,