A better way to produce 400x240 1-bit images

Library of images to use as OFFIMG screens on the DM41X and DM42
Forum rules
Do you have a creative streak? Post your OFFIMG photos here.

Images MUST be in Windows-NT .bmp format at a resolution of 400x240 pixels and 1-bit colour depth or they will not be displayed by the DM42. Images that do not meet this requirement will be removed from the forum :)
Post Reply
RJvM
Posts: 14
Joined: Wed Jun 02, 2021 9:21 am
Location: Apeldoorn, Netherlands

A better way to produce 400x240 1-bit images

Post by RJvM »

Hi,

I have noticed many of the images are very black and white, not very subtle, although some are allright. My way to produce better looking images is to use a macOS-based tool called HyperDither, which is based on Bill Atkinson's ancient original Macintosh rendering algorithm.

This gives great results, in my opinion. For example, the image bounds-union.bmp looks far better than the one pre-installed on the calculators, IMHO.

Converting the PNG to a 1-bit BMP turned out to be something of a challenge, I ended up using ImageMagick (Homebrew installation), this works fine, once you get the hang of it. Anyway, I include a few examples of images I made using this method, maybe interesting for other users, or helpful, etcetera. Regards!
Attachments
bounds-union.bmp
bounds-union.bmp (12.25 KiB) Viewed 457 times
magic-cap.bmp
magic-cap.bmp (12.25 KiB) Viewed 457 times
stuwdriel.bmp
stuwdriel.bmp (12.25 KiB) Viewed 457 times
User since 1976 (HP-25) and 1980 (HP-41) and a collector for many years I now own all the important ones: HP-35, 45, 55, 65, 67, 97, 21, 25, 34, 10-16, 41, 71, 48, 50, ... The wonderful DM41x calculator has made me look forward to new calculators again!
User avatar
RAPo
Posts: 271
Joined: Wed May 03, 2017 6:54 pm
Location: The Netherlands
Contact:

Re: A better way to produce 400x240 1-bit images

Post by RAPo »

Thd Driel photo is great, I loved to wander there when I was living in Arnhem. The stew is also called the faucet of the Netherlands.
DM41X beta: SN00018.
DM41X: SN00496.
DM42 beta: SN00074.
DM42:SN06020.
DM10L: SN056/100.
DM11L: SN 02058.
DM15L: SN2074.
DM16L: SN2156.
DM15, DM16, DM41
and a whole bunch of the original HP's,
RJvM
Posts: 14
Joined: Wed Jun 02, 2021 9:21 am
Location: Apeldoorn, Netherlands

Re: A better way to produce 400x240 1-bit images

Post by RJvM »

Thanks, the stuw-driel is based on my own photograph.
User since 1976 (HP-25) and 1980 (HP-41) and a collector for many years I now own all the important ones: HP-35, 45, 55, 65, 67, 97, 21, 25, 34, 10-16, 41, 71, 48, 50, ... The wonderful DM41x calculator has made me look forward to new calculators again!
EM41
Posts: 176
Joined: Mon Mar 30, 2020 12:10 am
Location: Overijssel Netherlands

Re: A better way to produce 400x240 1-bit images

Post by EM41 »

I use GIMP (picture/modus/indexed/use 1 bit palette), there are a few colour approximation methods but no real dithering as far as I can see.
HP41C (2x), HP41CV, HP41CX, DM41X β, DM41X, DM42, HP11C, HP48G, HP97
Thomas Okken
Posts: 938
Joined: Tue May 02, 2017 5:48 pm
Location: United States
Contact:

Re: A better way to produce 400x240 1-bit images

Post by Thomas Okken »

RJvM wrote:
Sun Jun 20, 2021 4:42 pm
Thanks, the stuw-driel is based on my own photograph.
Nice picture! It looked familiar even though I've never been to Driel, but it turns out that the ones at Amerongen and Hagestein look exactly the same. I must have visited the one at Amerongen on a high school field trip.

(Note: The English word for "stuw" is "weir.")
Panchdara
Posts: 14
Joined: Sat May 15, 2021 9:02 am

Re: A better way to produce 400x240 1-bit images

Post by Panchdara »

EM41 wrote:
Sun Jun 20, 2021 4:56 pm
I use GIMP (picture/modus/indexed/use 1 bit palette), there are a few colour approximation methods but no real dithering as far as I can see.
Yes. Resize (Scale) the image first then "Image/Mode/Indexed.../Use black and white (1-bit) palette" But, as you say. no obvious dithering. Thanks though. 👍
rprosperi
Posts: 1133
Joined: Mon Apr 24, 2017 7:48 pm
Location: New York

Re: A better way to produce 400x240 1-bit images

Post by rprosperi »

Thomas Okken wrote:
Sun Jun 20, 2021 11:28 pm
RJvM wrote:
Sun Jun 20, 2021 4:42 pm
Thanks, the stuw-driel is based on my own photograph.
Nice picture! It looked familiar even though I've never been to Driel, but it turns out that the ones at Amerongen and Hagestein look exactly the same. I must have visited the one at Amerongen on a high school field trip.

(Note: The English word for "stuw" is "weir.")
These weirs are new to me, very cool. I've just perused about 50 photos of these, they are certainly well-photographed and it appears they are frequent tourist and sight-seeing targets. Is there some special history behind them, I've never seen anything like these.

Thanks for sharing these notes, very interesting.
--bob p

DM42: β00071 & 00282, DM41X: β00071 & 00656, DM10L: 071/100
Thomas Okken
Posts: 938
Joined: Tue May 02, 2017 5:48 pm
Location: United States
Contact:

Re: A better way to produce 400x240 1-bit images

Post by Thomas Okken »

The reason for these is to maintain a more or less constant water level along the length of the lower Rhine. The water flow through the Rhine is very seasonal, because of the effect of snow melting in the Alps in spring and because of seasonal variations in rainfall in the upper watershed.

Thanks to the weirs, the water level can be kept high even when there isn't much flow, so shipping can continue even in the driest part of the year. The Rhine is a major transportation artery, connecting the port of Rotterdam to the industrial heartland of Germany, so this is rather a big deal.

I'm sure flood control and drinking water supply are also factors, the latter in particular, since the Rhine is a major source of drinking water for a big part of the country.
User avatar
RAPo
Posts: 271
Joined: Wed May 03, 2017 6:54 pm
Location: The Netherlands
Contact:

Re: A better way to produce 400x240 1-bit images

Post by RAPo »

I'm working for the state organization, called RWS, that is maintaining them. See https://www-rijkswaterstaat-nl.translat ... to=ajax,nv for more info.
DM41X beta: SN00018.
DM41X: SN00496.
DM42 beta: SN00074.
DM42:SN06020.
DM10L: SN056/100.
DM11L: SN 02058.
DM15L: SN2074.
DM16L: SN2156.
DM15, DM16, DM41
and a whole bunch of the original HP's,
Post Reply