Creating offimage

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Geoff Quickfall
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Creating offimage

Post by Geoff Quickfall » Thu Nov 23, 2017 9:39 pm

Hello,


I am trying to create some offimage but without success.

I have the following software and iOS:

- Latest windows 10.

- adobe photoshop.

I have been taking a JPEG image, converted to grey scale, created bmp. Reduced pixels to 400 by 240 at 70 pixels resolution. Is there a built in windows app that may help?

So:

Has anybody created or can create a step by step guide for offimage production.


Thanks, Geoff

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Vitasam
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Re: Creating offimage

Post by Vitasam » Thu Nov 23, 2017 10:05 pm

Geoff Quickfall wrote:
Thu Nov 23, 2017 9:39 pm
Hello,


I am trying to create some offimage but without success.

I have the following software and iOS:

- Latest windows 10.

- adobe photoshop.

I have been taking a JPEG image, converted to grey scale, created bmp. Reduced pixels to 400 by 240 at 70 pixels resolution. Is there a built in windows app that may help?

So:

Has anybody created or can create a step by step guide for offimage production.


Thanks, Geoff
You need 1-bit black&white image but not a grey-scale. Just open you image in Windows Paint, go File -> Properties -> Colors -> Black and White.
(though more advanced solution is to use e.g. Gimp with its dithering algorithms)
Elektronika MK-61, Elektronika MK-52, HP15c LE, DM42 SN#16 FW 3.13

Geoff Quickfall
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Re: Creating offimage

Post by Geoff Quickfall » Thu Nov 23, 2017 10:15 pm

Thanks

Will give it a try


Geoff

Geoff Quickfall
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Re: Creating offimage

Post by Geoff Quickfall » Thu Nov 23, 2017 11:06 pm

well i just don't get it, must be an off day.

i am trying to convert this image to offscreen:

Image

now it is a .png image so off to paint i go:

and i get this:

Image

yuk but okay. shrink to fit and no joy!

any suggestions?

rprosperi
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Re: Creating offimage

Post by rprosperi » Fri Nov 24, 2017 12:02 am

Geoff - set the file properties (400 x 240 and color to 1 bit depth) before you paste images in (or edit them, etc.) and it will generally come out as you're expecting; changing it after you're done all the editing/pasting, etc. produces the yucky images as it tries to dither down to 1-bit.
--bob p

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Geoff Quickfall
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Re: Creating offimage

Post by Geoff Quickfall » Fri Nov 24, 2017 12:14 am

aye aye sir! :D

Thomas Okken
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Re: Creating offimage

Post by Thomas Okken » Fri Nov 24, 2017 2:25 am

If at any point you are offered choices of how to perform the conversion to 1-bit, be sure to choose Floyd-Steinberg (a.k.a. Error Diffusion) dithering. This almost always gives the best results on monochrome screens. (For printing, clustered-dot dithering is often better, if the pixels have a tendency to spread out slightly as the ink is absorbed by the paper.) Your yucky pictures look like the conversion was simple thresholding, which almost always looks awful, and which sadly is MS Paint's standard M.O.

I am not familiar with Photoshop so I can't tell you exactly how to make it do Floyd-Steinberg dithering, just that that's the option to look for. Should you be comfortable with Linux or Cygwin, I could provide more concrete advice -- I still swear by NETPBM for this kind of thing.

EDIT: Oh, and be sure that the conversion and dithering are performed after stretching or cropping the image to the desired size!

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Mark Hardman
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Re: Creating offimage

Post by Mark Hardman » Fri Nov 24, 2017 3:04 am

How is this?
norebbo-1bit.png
norebbo-1bit.png (9.3 KiB) Viewed 1765 times
norebbo-1bit.zip
(3.17 KiB) Downloaded 59 times
DM42 S/N: 00043 (Beta)
DM42 S/N: 00065 (Beta)
DM42 S/N: 00357

Geoff Quickfall
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Re: Creating offimage

Post by Geoff Quickfall » Fri Nov 24, 2017 3:34 am

ha,

Mark, that is it, thanks.

now, if i may trouble you, what did you use to convert?

cheeers, Geoff :ugeek:

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Vitasam
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Re: Creating offimage

Post by Vitasam » Fri Nov 24, 2017 6:43 am

Thomas Okken wrote:
Fri Nov 24, 2017 2:25 am
If at any point you are offered choices of how to perform the conversion to 1-bit, be sure to choose Floyd-Steinberg (a.k.a. Error Diffusion) dithering. This almost always gives the best results on monochrome screens. (For printing, clustered-dot dithering is often better, if the pixels have a tendency to spread out slightly as the ink is absorbed by the paper.) Your yucky pictures look like the conversion was simple thresholding, which almost always looks awful, and which sadly is MS Paint's standard M.O.

I am not familiar with Photoshop so I can't tell you exactly how to make it do Floyd-Steinberg dithering, just that that's the option to look for. Should you be comfortable with Linux or Cygwin, I could provide more concrete advice -- I still swear by NETPBM for this kind of thing.

EDIT: Oh, and be sure that the conversion and dithering are performed after stretching or cropping the image to the desired size!
I'm using GIMP for color indexing and dithering.
https://docs.gimp.org/en/gimp-image-con ... dexed.html

And yes - stretching and cropping of the image is a very first operation.
Elektronika MK-61, Elektronika MK-52, HP15c LE, DM42 SN#16 FW 3.13

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