Image preparation

Dr Henry Knipe and A.Prof Frank Gaillard et al.

Images are clearly a very important part of and we aim for high quality and uniformity across the site. As always patient anonymity is essential, and any images with patient details included will be removed.

  • JPG: small size but degraded by compression; use quality of 80 or above to minimise image degradation
  • PNG: non-lossy, reasonable size, preferred format for diagrams, as edges and text will be crisp accepts (essentially) any size and then resizes it to serve up to viewers. Thus uploading a larger size, particularly native modality resolution is recommended. 

  • CT: 512 x 512 px
  • MRI: sequence specific ranging from 128 to 1024px
  • x-ray: variable ~ 1600 x 1600px
  • ultrasound: 512 x 512px
  • mammography: 2048 x 2048px
  • angiography (DSA): 1600 x 1600px

If in doubt upload a larger image. We keep all the original images.

Please keep images close to a square aspect ratio. It makes sure that the thumbnails and displayed images are relatively uniform. If your image is tall and thin (e.g. limb x-ray) then either combine two views in the one square image (see example 1) or add black space around the sides to make the image square (see example 2). This adds very little to the overall size of the image.

In general please have only one image/slice/projection per image. This is especially the case for cross-sectional imaging. The exception is long/thin x-rays (e.g. limbs) which often are better presented as side by side views.

For cross-sectional images (CT and MRI) or temporal sequences (DSA run), sequential images can be uploaded as a single .zip file containing sequentially numbered images (see example 3). See stacks for more information.

Taking photos of printed film is tricky, but with a little practice, reasonable results can be obtained.

  • camera settings
    • black/white (you can convert to greyscale later too)
    • macro
    • high-quality jpg (90 or 100)
      • you can .raw or .tiff -> png but this is of limited utility as JPG image degradation is not the quality limiting step
  • tripod ideal
  • glare from next to the film is horrible so need to mask it out
    • for CT/MR which are the standard size a hole cut in card works fine
    • for odd shapes need to be more inventive
  • reflections may not be apparent until you look at the image, so a pitch black room except for the lightbox is best, and even then you may see a reflection of yourself
  • autofocus often does not work (fluffy images) so focusing on a sheet of paper with lines drawn on it placed in front of the film works well; alternatively set your focus to the central dot, and aim initially at the patient demographics (remember to exclude these or edit them out later)
  • it can be really hard to replicate a nice flat image when there is dense bone (when the film is completely transparent you get a lot of glare and can't see the rest; see example 4)

A number of tools are useful to make sure your images are the best they can be (for and for publication)

  • Picasa 3
    • free
    • great program for organising your photos, but limited functionality
    • (Windows, Linux and Mac)
  • Seashore
    • lightweight GIMP (see below)
    • does everything you need it to, fast and easy
    • Mac only
  • Photoshop
    • not-free... not even close
    • the 'gold standard' of photo editing software
    • (Windows and Mac)
  • Gimp
    • free
    • opensource alternative to photoshop
    • (Windows, Linux and Mac) 
  • Irfan viewer
    • free
    • powerful image converted (great for batch processing images)
    •  (Windows only)

If you do not want to install software on the computer you are using you can use online browser-based programs of which there are dozens.

    • free
    • lets you crop and convert to grey scale
    • free,
    • lets you crop and annotate
  • Windows right click - add to archive
  • Mac right (secondary) click - compress to archive
  • 7zip - - powerful opensource easy to use archive utility (Windows, Linux and Mac)
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