Simulate bitmap mode in photoshop for e-ink photo preparation

Question

I need to prepare some photos for an e-ink display. The display is 1-bit. Each pixel is either 100% black or 100% white - there is no gray.

I know that I can change the mode of my photos in Photoshop to bitmap, and it will present a number of options as to how the dithering and noise are handled. But this process is destructive.

Is there a non-destructive way to simulate this in Photoshop?

I tried using the Halftone filter in Grayscale mode, but this makes circles instead of pixels, and doesn't have any dithering options.

I can't be the first person to need this - am I doing it wrong?

Adding some examples below.

I'm using an e-ink display from Waveshare. It's 800x400 at approx 49 pixels/cm, 1-bit bitmap. So I've set up my Photoshop document like this:

8 bit grayscale:

I want to be able to try out different 1-bit bitmap "looks", without destroying the original layer:

eg, Halftone screen settings like this:

gives this kind of result:

But a diffusion dither, gives a different look:

I would like to simulate all of these different looks in a grayscale document, without having to destructively edit my image each time.

I can use the Halftone Pattern filter on my original image, but it doesn't offer the same settings as the 1 bit bitmap conversion, and looks different:

Answer 1

There is no Filter in Photoshop that simulates the different Bitmap mode methods.

You can't really simulate any color mode with a filter (but Grayscale mode can of course be simulated by desaturating the image and CMYK mode can be simulated with Proof Colors).

You might think that you could convert your image to a Smart Object and then convert to Bitmap mode to retain the possibility to edit the original image and see the changes reflected in the bitmap version, but that's not possible. Bitmap mode requires the image to be flattened.

This is unfortunate, and I sometimes feel Photoshop easily could have some possibilities to work non-destructively in Bitmap mode, but I guess it's not a priority.

Idea for a workaround

If you want this non-destructive simulation in order to be able to dynamically finetune the conversion to Bitmap mode, I see no way. But if you are interested in quickly getting a preview of a specific conversion, I have this proposal:

• In the Actions panel, Click Create new set to make a set of "Bitmap conversion preview" actions, click Create new action (optionally choose a Function Key, you can change this later) and click Record to start recording.
• Select > All.
• Edit > Copy Merged.
• File > New. Click OK.
• Edit > Paste.
• Layer > Flatten Image.
• Image > Mode > Bitmap.
• Choose the desired Method. Click OK.
• Select > All.
• Edit > Copy.
• File > Close. Click No.
• Select > Deselect.
• Edit > Paste.
• In the Actions panel, Click Stop playing/recording to end the recording.

Now you have an action which will create a new layer with a bitmap version of your image with the chosen method. Run it from the Actions panel or use the specified Function Key. To remove the preview layer just Edit > Undo.

You can create actions for each Bitmap conversion method you want to be able to preview.

Answer 2

Ximagic Photoshop plugins for Mac and Windows contain something you may want http://www.ximagic.com/g_index.html Check the GrayDither Toolbox. It's a commercial product, but here's a screenshot of the dialog of trial version:

Here's a zoom in view of the conversion result (still RGB, must be converted to bitmap mode manually):

Martin Koch Verlag has a comparable plugin with lower cost. Their version has fewer conversion principles, but there's some image enhancing adjustments. Unfortunately they do not have a 64 bit version.

There exists a freeware route: Jump out of Photoshop. Get Krita (freeware). It has G'mic filter package which knows several B&W conversions and can show a plausible preview without actually modifying the image. Change the filtering settings freely and press Cancel or OK when you have seen enough. Note that if you press OK the image is still in RGB mode. Change the mode to bitmap separately.

An example: Here's a flower photo which is cropped to 800 x 400 pixels:

G'mic dithering filter shows this preview:

NOTE: There are sliders to adjust the brightness scale to fit the dithering process and optional colorizing sliders in case one wants something else than dithering to plain black and white.

BTW. The main application of Krita is painting, but it understands numerous other things that advanced users surely find useful.

Important: G'mic collection is today also available as a plugin for Photoshop as user Billy Kerr commented after this answer. He gave these links: G'MIC https://github.com/0xC0000054/gmic-8bf/releases and an example: https://i.stack.imgur.com/W9fnY.jpg

Answer 3

Those dithering patterns are very specific to image modes - bitmap or Indexed colour, and as far as I know there's no way to apply them using filters non-destructively.

However, as long as you are not looking for an exact representation of true dithering, you can get something that kind of looks similar using pattern and levels layer adjustments.

Here's an example

I applied a Pattern adjustment layer, the pattern I chose is called "Cold Press", and then I set its blending mode to Vivid Light, then add a Levels adjustment, and tweaked the levels to increase the contrast of the pattern. You could perhaps experiment with the blending modes, Hard Light might work too, or use different patterns.

Answer 4

Well, it is possible offcourse to make your own halftone pattern. The first thing you need to do is a pattern where you want to "animate" the sequence of the shape so that you allways increment it by pixel value for each intensity. I have made following example (note its not perfect because i did it in a few minutes. Nor was it intended to be perfect, you have to make your own)

Image 1: the halftone program pattern

Then you put a black and white layer a levels layer and a pattern fill layer with screen mode of hard mix. Thats it. Ok so you can add a maximum filter or mosaic in the layer stack too to make the pattern less noisy if you wish. Example:

Image 2: Sample image from deviantart image CC BY FlemmingHansen.com

Image 3: Demo result

A lot of work sure to adjust to be same as the inbuilt halftoning, can be done. But i mean how much do you really need this. On the other hand you can make Escher patterns too if you wish.

Answer 5

Got an idea that might do what you need : Change the blending mode of your layer to Dissolve. Then copy your layer in your clipboard (ctrl+a and ctrl+c) and paste it in a Layer mask (option/alt click on the empty mask to go in, and paste) then invert it.

Then to have full black or white, you create a full black clipping mask on top of this.

You can now adjust the rendering by manipulating the levels on the Layer Mask

Answer 6

I, personally, would blow right past any halftone...
I wouldn't want a pattern which is specifically what a halftone is going to create.

I would explore using Filter > Filter Gallery > Reticulation
and Filter > Pixelate > Mezzotint

Original...

Desaturate (and auto-Levels) then run Reticulation filter...

^{For this image...}

Desaturate (and auto-Levels) then run Mezzotint filter...

Combine the Reticulation and mezzotint layers, adjusting blending for the mezzotint...

Reduced 50% upon output (save for web)...

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Converting the image to a Smart Object will allow you to do all of this on a single Object. Basically, it applies the alterations non-destructively to a single layer via Adjustment Layers and Smart Filters.

You could then, if desired, merely swap out the Smart Object contents and have the same effect for a new image and alter the filters a bit if necessary.