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i'd been googling for answers for this, all guides point me to make it grayscale, but actually it is still not enough, it still allows non-black(gray gradient). What I want is

Suppose I ended up having this image: a perfectly round circle done via ellipse tool and stroke path

enter image description here

Then I want to make sure if a pixel is not white then make it black. So what I want should be like this:

enter image description here

I ended up learning the use of sharpen but it still not works, it just make the gray more black PLUS it adds more feather so even sharpen fails me to accomplish this.

Hope somebody can help and guide me how to do this. Thanks~

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  • 6
    You can use the LEVELS too, CONTRAST tools, you can convert to BMP mode. There are several ways. I'd start with LEVELS.
    – DA01
    Commented Jun 25, 2015 at 14:02
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    @DA01 thanks I've done it via: Max the LEVELS PLUS max the CONTRAST then convert to BMP mode. please reply with this answer I'll mark yours as the answer. Thanks!
    – arvil
    Commented Jun 25, 2015 at 14:17
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    You could press Ctrl + Shift + S and then save the image as an .png file that only contains 2 diffrent custom-set colors. (Black and White)
    – BlueWizard
    Commented Jun 26, 2015 at 9:24

6 Answers 6

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You want the Threshold function. It lets you set a cutoff value, where all pixels lighter than that value become white, and all others become black.

The Threshold function can be found at Image>Adjustments>Threshold.

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    This is the right answer, but this is graphics design, you should add a file menu breadcrumb an define the how to use the tool or beginers will just think you are talking mumbo jumbo.
    – joojaa
    Commented Jun 25, 2015 at 23:32
  • Downvoted because for this answer sounds like mumbo jumbo. I tried all threshold values from 1 to 255 and couldn't create a black-and-white result.
    – q9f
    Commented Feb 13, 2017 at 14:29
  • This is not the right answer. As the previous commenter stated, the only thing this is doing is making my grey pixels whiter, not absolute white.
    – arkon
    Commented Oct 5, 2023 at 9:15
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You'll want to change your image mode to 'indexed'...

enter image description here

and then choose black and white:

enter image description here

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    Won't that make light gray pixels white though? This uses a 'nearest color' algorithm. Still a good idea, as you can create an exact palette and then simply change all palette entries "not white" to black, which only takes a few clicks.
    – Jongware
    Commented Jun 25, 2015 at 15:08
  • @Vincent i agree about the nearest color algo it ended up still far from my desired output above i.imgur.com/UQF0DHj.png
    – arvil
    Commented Jun 25, 2015 at 15:15
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There are a lot of considerations, but at the base level, set the image to a mode that doesn't allow anything but black and white. This is how it's done in Photoshop:

If the image is in RGB mode, you first convert to Grayscale mode. Choose Image > Mode > Grayscale. Photoshop asks to discard color information. Click "Discard."

Now, choose Image > Mode > Bitmap. A rendering options dialog box appears. Choose the resolution and the method of simulating grays, and then click OK.

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The issue isn't how to convert it into black and white but what you should do from the get go to make sure it is black and white. What you have is feathering around your image. This is usually from the brush tool as Photoshop is trying to blend the image into the background. If you use the pencil or a brush with 100 hardness then this will not occur.

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  • I've done the "black" using a brush tool with 100% hardness actually.
    – arvil
    Commented Jun 30, 2015 at 6:46
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This might be late but, save it as .bmp, open it in paint, save as monochrome bitmap, open again in photoshop. Hope it helps.

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Follow the steps:

Open the image you want to change

Go to Image --> Mode --> Bitmap

NOTE: If you're using RGB COLOR first you need to put in grayscale (Image --> Mode --> Greyscale, Discard color info)

Click Ok in the Flatten Lines message box

After that, in Method Use: 50% Threshold

That's all

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