How to convert images to black & white?

[jillownsamac]

What is the best (cheapest, easiest) way to convert JPG's and PNG's to Black and white, preferably, with the option to batch convert a bunch of files). I'm not all that concerned about image quality (if it degrades slightly) as long as it is black and white and I have some control over the contrast. (I want my whites, white and my blacks, black, like

#ffffff & #000000).

It seems like some of the advice that I have seen online says to use Preview. I can't seem to find the option for doing that specific thing (or much of anything in Preview) anymore? I did find the color adjust and it seems like I can somewhat simulate something that is at least more black and white, but I'm not sure, that's really the same thing or that what that will do, will work for my project. I feel like that much older versions of preview might have done more (much older). Is Preview less robust than it used to be?

 

[Slartibart]

just to be sure to help in the right way: you want grayscale pictures or monochrome pictures (or dithered black and white ones)?

 

[HobeSoundDarryl]

There are many apps with tools to do this, but simple & free...

1. Open in Preview, which comes with macOS.
2. Tools (menu), Adjust Color...
3. Grab the Saturation color handle and drag it to the extreme left. Result will be colorless grayscale.

Apple's included Photos app also has editing tools which will let you do the same with a click, and filters for a couple of variations of grayscale...

Note your description of wanting only #000 and #FFF as colors implies you don't want grayscale but only black & white colors- no grays. If so, you can then select "File" (menu), "Export" in Preview, select Format: PDF, Quartz Filter: Black & White and that will give you a typically pretty ugly, B&W-colors-only image for free (same image as above in only Black & White by this method)...

Other software could dither B&W to still yield a B&W image that will look better than that one.

Lastly, there are websites that can do this for you. For example, I tried this one and it worked just fine.

 

[kryten2]

Quartz Composition Filter as mentioned by HobeSoundDarryl can also be found in Automator.

Info: using-your-macs-built-in-photo-filters