Poor-man’s sepia conversion


Working for Pixagogo makes digital imagery my daily bread, and I fool around with images every now and then. I am, however, not a user of PhotoShop. I’ve never worked with it, I don’t own the software, nada. Keep that in mind while you continue reading this.

Recently, for my cousin’s filmfilostoverij blog, I converted some film snapshots into small thumbnails like the one on the right (from “Lucia y el sexo”). The program I use for conversion is IrfanView. Not the best program, not the most complete, but easy, stable and free. For the stuff I need to do, I find Gimp too complex.

What I did to the images was:

  1. crop a square part of it
  2. convert to grayscale
  3. resize to 400×400 px
  4. perform a median filter (value: 9)
  5. resize to 100×100 px
  6. Save as JPG

But then I wanted to have a ‘sepia‘ effect. Irfanview does not have it. I wanted it. So I began my quest.


I started with the ‘Enhance Colors’ function and added 64 ‘R’ and 16 ‘G’ to the B/W image, but that didn’t look real enough. What does sepia look like, anyway? I found two definitions, expressed in CMYK coordinates, that I converted to RGB with my CMYK-to-RGB converter hizmo (thanks to Wikipedia):

The color
1. definecolor{Sepia}{cmyk}{0,0.83,1,0.70} (from TexCeh)
#4D0D00 (77,13,0)
2. sepia cmyk(0%, 60%, 81%, 63%) (from december.com)
#5E2612 (94,38,18)
In ‘websafe‘ colors, this would be:
#551100 (84,17,0)

So let me show you how I proceeded, using an image of my tango teachers, Marisa y Oliver:

original image
Original
  1. Convert to greyscale
  2. Enhance colors: 94-38-18 (#5E2612)

=> way too red!

  1. Convert to greyscale
  2. Enhance colors: 77-13-0 (#4D0D00)

=> color OK, but too light

  1. Convert to greyscale
  2. Enhance colors: 77-13-0 (#4D0D00)
  3. Add 50% contrast

=> looks great

    Compare this with the optional QuickSepia plugin

=> I like mine better

Voila, there it is, a simple poor-mans sepia, that can even be used in ‘batch convert’ (Irfanview).

Short CMYK/RGB explanation and Detailed CMYK/RGB explanation

[Listening to: “The Prettiest Thing” – Norah Jones – Feels Like Home]

4 thoughts on “Poor-man’s sepia conversion”

  1. Peter,
    Thanks for posting the great explanation regarding sepia ‘conversion’ in Irfanview. It will be most helpful. It’s great information!
    I’ve been a fan of Irfanview for years, and can do almost everything I need to do with an image with Irfanview. (For those times when I need more editing power, I use another freeware prog called PhotoFiltre. I find PhotoFiltre easier to use than Gimp, PSP, or Photoshop.)
    Anyhow, thanks again for the great info… it’s a keeper!

  2. You’d think that irfanview would just have sepia conversions built in by default, but unfortunately… not the case.

    Fantastic and very helpful explanation… thanks for sharing it!

  3. binnekort hebt ge uwe mac en zijn al die alternatieve oplossingen overbodig en leert ge misschien “the real stuff” kennen. (zijn niet moeilijk hoor…)

  4. hey we r doing project on post processing on videos….
    we r doing it in C language.. i need equations to convert yuv video into sepia toned image…. can u help???

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