Using AI to Adjust Colour

#1 · December 23, 2025, 1:02 pm

Quote from Steve on December 23, 2025, 1:02 pm
I was recently notified ny my friend Bob Hill that he had found two postmarks that I might be interested in. One was a Last Recorded date of use for Alice; the other, an Indian Office Pietermaritzburg postmark unlisted in Putzel. I asked him to send me a printout because he does not have a scanner. The printout I received from Bob came with an apology for his printer "not printing red".

No trouble, I thought. I will run it through Chat GPT and ask it to automatically adjust the colours.

I attached a JPG file at 300 dpi resolution and instructed ChatGPT with the following:
The attached scan is from a printer that is not printing 'red'. Please restore the image to the correct colours. As a guide, the top stamps are from the Union of South Africa 1942 - 1944 'Bantam' (War Effort') issue. The 6d yellow stamps should be orange red. The registered letter from Alice bears a 1913 6d King's Head which should be black and violet. Good luck!

Now, I accept that my instructions could have been better, more concise, more techically demanding. This is the result I got.

There are a couple of points to note from this exercise. Instead of downloading ChatGPT's work I copied it from the screen as a 72 dpi file. This meant it was less detailed than the 300 dpi file I submitted. This is my fault. I want a quick fix. Annoyingly, ChatGPT did its thing, quirkily changing one of the 3d blue Bantam stamps to red. I assumed it would leave them alone. It did not. However, it did get the 6d Welder into a nice shade of orange-red. The 6d black and violet King's Head is not great but it is more recognisable now as a Union stamp. What is disappointing is that the blue manuscript registration writing has been changed to red - but not the vertical and horizontal rehistration lines. It should know not to do this! It has also trimmed the image. Irritations like this make AI frustrating to use at present.

Hopefully, by giving it tasks like this it will learn and get better at it in future. Howver, I am too busy to tell it why and where it has screwed up. This is somewhat counter-productive as it must be instructed if it is to improve. I cannot expect others to do this for me (any you!) Nevertheless, I will keep hoping that one day it will provide a useful quick fix shortcut to what I want. Rating 4 / 10.

For anyone interested in these postmarks there will be a short article in UNRECORDED DATESTAMPS / EARLIEST USE soon.

I was recently notified ny my friend Bob Hill that he had found two postmarks that I might be interested in. One was a Last Recorded date of use for Alice; the other, an Indian Office Pietermaritzburg postmark unlisted in Putzel. I asked him to send me a printout because he does not have a scanner. The printout I received from Bob came with an apology for his printer "not printing red".

No trouble, I thought. I will run it through Chat GPT and ask it to automatically adjust the colours.

I attached a JPG file at 300 dpi resolution and instructed ChatGPT with the following:
The attached scan is from a printer that is not printing 'red'. Please restore the image to the correct colours. As a guide, the top stamps are from the Union of South Africa 1942 - 1944 'Bantam' (War Effort') issue. The 6d yellow stamps should be orange red. The registered letter from Alice bears a 1913 6d King's Head which should be black and violet. Good luck!

Now, I accept that my instructions could have been better, more concise, more techically demanding. This is the result I got.

There are a couple of points to note from this exercise. Instead of downloading ChatGPT's work I copied it from the screen as a 72 dpi file. This meant it was less detailed than the 300 dpi file I submitted. This is my fault. I want a quick fix. Annoyingly, ChatGPT did its thing, quirkily changing one of the 3d blue Bantam stamps to red. I assumed it would leave them alone. It did not. However, it did get the 6d Welder into a nice shade of orange-red. The 6d black and violet King's Head is not great but it is more recognisable now as a Union stamp. What is disappointing is that the blue manuscript registration writing has been changed to red - but not the vertical and horizontal rehistration lines. It should know not to do this! It has also trimmed the image. Irritations like this make AI frustrating to use at present.

Hopefully, by giving it tasks like this it will learn and get better at it in future. Howver, I am too busy to tell it why and where it has screwed up. This is somewhat counter-productive as it must be instructed if it is to improve. I cannot expect others to do this for me (any you!) Nevertheless, I will keep hoping that one day it will provide a useful quick fix shortcut to what I want. Rating 4 / 10.

For anyone interested in these postmarks there will be a short article in UNRECORDED DATESTAMPS / EARLIEST USE soon.