Yesterday I tooted that I had discovered an 1852 edition of George Robertson Glieg's the Subaltern in the Athenaeum's historic book collection.
Glieg had an interesting career eventually ending up as Chaplain-general of the army and was also involved in the Canterbury association, an association of mid Victorian Anglican gentlemen and clergy that wanted to plant a godly Anglican colony on the south island of New Zealand, and who eventually settled what is now Christchurch in NZ.
Glieg himself never moved to New Zealand and spent most of his life in England.
Given that the date of publication - 1852 - is quite early and predates the founding of Stanley, we can wave our hands and say that it was probably one of the first books acquired by the Athenaeum, and the general historic interest around Glieg, it's a pity that my initial photograph taken with my phone for documentation purposes was quite poor.
The lighting in the Athenaeum is problematic, and tends cast shadows. The obvious answer would be to retake the picture using a light box to ensure even illumination, but in the meantime I decided to have a little play with ImageMagick to see if I could improve the image.
Why ImageMagick?
Two reasons. Most of the online image tweaking tools don't really do shadow equalisation - they can blur and remove shadows, but not normalize them, and besides they want you to sign up - often using your facebook/google/apple login credentials, and I'm not keen on that.
Secondly I have ImageMagick installed on the big old iMac I have running ubuntu.
So, first of all I did a simple command
magick glieg.jpg -auto-gamma output1.jpg
that improved things slightly but not massively, so I then took the output1.jpg image and reprocessed it further
magick output1.jpg -clahe 50x50%+256+2 outc.jpg
which produced a slightly better image
you can still see the shadow, but it's not quite so intrusive.
Getting there I went through several iterations - increasing the clip limit (the +2 part of the command) produces a more contrasty image which is great if you're trying to bring up pencilled graffitti, reducing it makes the image a little more even.
So, not ideal, but a valuable exercise - probably more useful for the doing than the result as I've also now got reasonable experience of image manipulation to bring up faint scripts and markings, as it this example where I cranked up the clip limit to +7












