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Saturday, September 22, 2012

Photoshop tutorials for medical researchers: simple color conversion

I often get emails from my sister (who is a medical researcher) asking me how to do some very simple image processing tasks. I usually just do it for her but when she recently sent a file to me I thought that maybe it would be easier to just teach her how to do it so she can do it herself.

The task was really simple: convert a color graph against black background to a black graph against the white background. I did this in Cantonese with a mix of English because this is how we speak to each other – this video is really meant for her. But maybe when I have time I will go and add some closed-captioning.

Lessons learned from making this video:

  • As someone who has been using Photoshop since 1995, all the keyboard shortcuts are really second-nature, but for a complete n00b the learning curve is fairly steep.
  • I am on a Mac right now but my sister is on a PC. It is quite a mouthful to explain both.
  • I think conceptually and visually so I often have trouble spelling out what the functions are.
  • Found a nice Mac app for displaying keyboard / mouse press interaction: Mousexposé. Useful for both Skype screen share as well as video capture.
  • I used Screenflow 3 to capture the video but the audio track is in fact recorded separately. Process: audio was captured with the internal microphone. I clapped at the beginning to make a visual wave mark, and then I used my Sony PCM-M10 to record at the same time. I am doing it this way because I don't currently have a mini cable to connect the field recorder to the computer. Otherwise I probably would just connect the line-out directly to computer.
  • The audio file from the PCM-M10 is then placed into Ableton Live and cleaned up with some EQ / mastering tweaks using iZotope Ozone. The finished 24-bit 96kHz aiff is then exported and placed into Premiere where I visually matched the ‘clap’ mark and then I discard the bad audio from the video.

I know, it's a lot of steps – but if you don‘t want to deal with having to drive yourself mad to clean up audio from bad microphones with huge noise floors, this is the way to do it!

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