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I know I can very easily export an image to PNG 8bit with just a single color channel in Gimp. But I can't figure out how to do that in Photoshop. "Export as" gives an option to reduce number of bits per channel but not to reduce number of channels,even in gray-scale mode.Can Photoshop do that without any external plugins?And if not,is there a free/commercial plugin that can do that?

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Using Save for web you can get a indexed one channel 8 bit .png image

Save for web

Index channel


If what you are looking for is a monochromatic image, the process is different

  • Menu Image > Mode > Grayscale
  • Menu Image > Mode > Duotone > Choose Monotone
  • Save for web > PNG-8
  • That's not true.If you load this file with a software which know to tell you number of channels you will see it comes with 3 or 4. I am a programmer and load that image using image loading API.From your example it reports 4 channels. Now,if you go to Gimp and export grayscale to PNG,you have an option called 8bpc GRAY.That one gives me exactly what I need - grayscale single channel 8 bit image. – Michael IV Oct 9 '18 at 11:13
  • Of course, the images I put in the answer are screenshots, .png rgb, 3 channels. But if you do the steps described in the answer you will get what you are looking for in your question – Danielillo Oct 9 '18 at 11:23
  • I tried totally grayscale (just black and white) image.Converted it both to grayscale and to duotone and that changes nothing.Please drop me an image you think is a product of the operations you specified,and I will tell you how many channels it has. – Michael IV Oct 9 '18 at 11:26
  • The second screenshot shows an image with a single 8-bit channel called Index that corresponds to an image indexed to 256 colors. – Danielillo Oct 9 '18 at 11:30
  • Man,please put in your answer a single channel image produced by your setup(and I will test it),otherwise it didn't happen. I am quite experienced with photoshop and other image editing software.So far,using all possible options in photoshop all I got was 3 or 4 channels images. – Michael IV Oct 9 '18 at 11:41
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Try this:

  • Make sure your image is in Grayscale mode.
  • Choose File > Save As.
  • Select png format and save the file.

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