ok, so the stretch contrast under the auto button automatically adjusts contrast? Am i understanding you correctly?
No, Colors > Auto > White balance... will do it (on B&W as well)
i eventually want to learn how to do it manually,
If you are selling you laser thing,
Yes! indeed IMHO you will need to learn to do it manually for example if a customer want to engrave something which appear in the colored photo, but disappear with all the "Auto" function in B&W, you will need to know how to make it appears when it becomes B&W.
I would recommend you to learn the "Levels" first (it's a simplest version of the Curves), the "Auto input levels" in that tools is exactly the same as the "Auto > White Balance..." I spoke above
2 quick links I found for a good start to learn "Levels":
https://patdavid.net/2011/07/getting-aro...ng-levels/
https://www.youtube.com/watch?v=U6kFhN4T8uc
but its hard for my eyes to see the difference with greyscale so i cant always produce the best images for laser engraving.
You are no obliged to start with a B&W, personally I would do Levels in Colors then use the mono mixer (Colors > Desaturate > Mono Mixer...) or use any desaturate method that give a quick result I'd like AFTER adjusting the color,
Why? because your conversion in black and white will always depend about colors and darkness/lightness of these colors.
I love this tool -> Colors > Desaturate > Mono Mixer
https://www.youtube.com/watch?v=_SdjdPGb4B0
But it's me only, if you don't like it, in the Colors > Desaturate menu you have other tools to chose from
Also when you have finished to adjust your B&W picture, you might want to take a look at this tool > Menu Colors > Threshold... If laser engraving is just made of black and white spots (no gray gradients), you might love this tool. But I do not have any idea what type of B&W you need to do laser engraving
No, Colors > Auto > White balance... will do it (on B&W as well)
i eventually want to learn how to do it manually,
If you are selling you laser thing,
Yes! indeed IMHO you will need to learn to do it manually for example if a customer want to engrave something which appear in the colored photo, but disappear with all the "Auto" function in B&W, you will need to know how to make it appears when it becomes B&W.
I would recommend you to learn the "Levels" first (it's a simplest version of the Curves), the "Auto input levels" in that tools is exactly the same as the "Auto > White Balance..." I spoke above
2 quick links I found for a good start to learn "Levels":
https://patdavid.net/2011/07/getting-aro...ng-levels/
https://www.youtube.com/watch?v=U6kFhN4T8uc
but its hard for my eyes to see the difference with greyscale so i cant always produce the best images for laser engraving.
You are no obliged to start with a B&W, personally I would do Levels in Colors then use the mono mixer (Colors > Desaturate > Mono Mixer...) or use any desaturate method that give a quick result I'd like AFTER adjusting the color,
Why? because your conversion in black and white will always depend about colors and darkness/lightness of these colors.
I love this tool -> Colors > Desaturate > Mono Mixer
https://www.youtube.com/watch?v=_SdjdPGb4B0
But it's me only, if you don't like it, in the Colors > Desaturate menu you have other tools to chose from
Also when you have finished to adjust your B&W picture, you might want to take a look at this tool > Menu Colors > Threshold... If laser engraving is just made of black and white spots (no gray gradients), you might love this tool. But I do not have any idea what type of B&W you need to do laser engraving