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 has initially created 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 X-ray computer tomography (CT) data.

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. The Visible Man data was made available in 1994.

The Visible Woman data is for a 59 year old woman who died of natural causes. This data was made available in December 1995.

For both the male and female, images of the body were first obtained using magnetic resonance imaging and computer tomography. It was then embedded in gelatin, frozen, and sliced crosswise into transverse slices, 1 millimeter wide for the male and 1/3mm for the female, 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.

Currently we are not utilizing the improved resolution for the female data - the vertical slices used were taken only every 1mm, like the male data, rather than the available 1/3mm slices. This may be changed in the future.

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 for the male and 39 Gbytes for the female (although we are currently using only using 1/3, or 13 Gbytes, of the female data).

We have cropped the original images and removed the gelatin background. The original data were transverse slices (axial view), and we have also reconstructed 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 degraded 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.

The Visible Human data set also includes MRI and CT data. We hope to incorporate this data in the future.