Tektronix 4050 Emulator - BITMAP image quad-resolution breakthrough!

[nikola-wan]

You can still learn or re-learn something every day

I was trying to figure out why my 4050 BITMAP images were too bright on the 405x Emulator - but running the viewer on the same image on my 4052 and 4054A showed a lot more detail.

I figured it out today - I had added a feature to the 405x emulator six years ago in March 2018 to double the width and double the height of each pixel to increase the brightness and visibility of the vectors and text.

My update is what caused the display issue with my bitmap images since adjacent "pixels" would clobber blank pixels and show "on" pixels.

First image below is the 405x Emulator displaying a scene from the 1968 sci-fi movie "2001 - Space Odyssey", where the two crewmen are discussing issues with the HAL computer. They moved into one of the PODs to keep HAL from overhearing - since HAL was voice-controlled. HAL was able to understand their conversation by reading their lips through the window of the POD that faced one of HALs camera 'eyes'.



Second image is the black-and-white bitmap dithered-dot image source image I had created, showing a lot more detail. Note the dots on the wall of the POD around the window are much smaller than the 405x Emulator image which is displaying 2x2 dots for each pixel in vectors and text.





Third attachment is the 405x Emulator with my modification to change the pixel size to 1x - single dot per pixel. You can see that the Title and Attribution text are also only single dot per pixel - which is not as bright as the four dots per pixel in the first image. But this image is dot-for-dot identical to the source bitmap!



I'll discuss with @WaveyDipole adding a button on the 405x emulator to change the pixels between quad-dots and single-dots for viewing bitmaps and high-definition vector images.

Since I was using the 405x Emulator in 100x speed (latest John Wavey experimental version - to run my 4050 BASIC program to create each of the R12 / Fast Graphics images from bitmap source images, I have been trying to improve the images by reducing brightness - but now I realize the problem has been my 'tweak' to the original 405x Emulator to increase brightness.

Brightness (or lack therof) has been an issue for 4050 computers since the introduction of the 4051 in 1975 and 4052 and 4054 introduction in 1979. They all had vector dot sizes to support 1024x780 resolution, and the 4054 had a dot size about the same size as the 4051/4052 because the display was almost twice as wide and twice as high at 19-inch diagonal compared to the 11-inch diagonal 4051/4052 display!

 

[nikola-wan]

Here is my screenshot running @daver2 original Tektronix 4051 emulator with my change to the dots for text characters to double the height and width of each text pixel - but not change the pixels for the lines. I had to go back to this March 2018 version of the 405x web-browser emulator to see my changes - so I could make them in the current 405x emulator.




Here is my screenshot of the latest experimental version of the 405x emulator on @WaveyDipole's repository - MODIFIED for single pixel TEXT and VECTORS - running @Philcogrump 's LINEs program:




and finally - here is the current UNMODIFIED version of the 405x emulator running LINES with 2x pixels for text and graphics



and here is the screenshot of the entire 405x emulator showing the entire user interface including the latest window size and speed buttons at the top left corner of the emulator window:




I just realized @WaveyDipole has just added an AUTO LOAD button at my request. Now you use the Storage button to load an entire directory or single file from my Flash Drive zip image and press the AUTO LOAD button to run the file 1 program - just like you would for a tape!

 

[nikola-wan]

Here is my 4054A screenshot of the two 2001 crew Discussing HAL:


There is bright "banding" on the chair cushions and a little bit of "banding" on their cheeks. I believe this is due to the writing beam energy of nearby dots increasing the stored energy of dots already written.

I have seen this before on some of my other bitmap pictures.

Otherwise - this image is much better than the current 405x Emulator image - and incredibly amazing for 1979 Tektronix 4054 technology. The IBM 8514 graphics adapter for their microchannel PCs was introduced in 1987 with 1024x768 256 color graphics but interlaced video at 43.5Hz with a bit of flicker! The first PC-compatible adapter with 1024x768 non-interlaced 60Hz graphics was the Compaq AG 1024 introduced in 1989 with a TI 34010 graphics accelerator.

My next step on improving 4050 bitmap images would be to try using the Option 30 coprocessor to write the dots instead of the R12 Fast Graphics ROM pack - this may greatly speed up the display of the pictures.

Or I might try reducing the bleed over banding by changing the order of R12 dots to eliminate writing adjacent R12 ON dots.

According to the timestamp on this photo and the previous photo in iCloud - this image took about 4 minutes to display on my 4054 with R12 Fast Graphics from a 481KB R12 BINARY file on my Flash Drive. This R12 bitmap is the maximum image size of 1024x780, which stored in R12 vector dots takes 3 bytes per dot for the 10-bit X and 10-bit Y coordinate. A full screen of ON dots would require 1024x780x3 bytes = 2,396,160 bytes! So this R12 bitmap image is about 20% of full screen ON dots!

 

[nikola-wan]

And in no time at all @WaveyDipole has updated the 405x Emulator to add a COARSE/FINE pixel size selector below the WINDOW size and emulator SPEED controls in the top left of the Emulator window.

https://github.com/Twilight-Logic/Tek405xEmulator/blob/master/experimental/JonStanley-Mod-Storage-Pix-20240427.zip

Here is my latest Mandelbrot bitmap with COARSE pixel selected in third icon on top left of Emulator window:




and here is the same Emulator, but with FINE pixel selected. RUN the current program again, selecting the Mandelbrot bitmap:



Both results are nice - but the FINE pixel image matches my source bitmap perfectly!

Right now the FINE pixel setting changes TEXT and VECTORs, but it really helps me make better bitmaps as the COARSE pixel view caused me to dim the images in the PhotoDemon editor too much.

When the images are displayed on real 4051/4052/4054 computers - the image looks like the second attachment!

 

[WaveyDipole]

Unfortunately, the text in "fine" mode did not look as nice although its appearance might perhaps be considered a bit "retro". With this in mind there is now a "mixed" mode, where text is rendered in a clear font while the image gets rendered in single pixel mode to get the best result from it. So here is that HAL scene again to demonstrate:



The same effect can be achieved with vectors. To compare, this is the standard mode:



Now, to compare, this is the same rendered in the new mixed mode:

Tek405xEmulator/experimental/JonStanley-Mod-Storage-Pix-20240427.zip at master · Twilight-Logic/Tek405xEmulator

Tektronix 405x Emulator. Contribute to Twilight-Logic/Tek405xEmulator development by creating an account on GitHub.

github.com

Enjoy!

 

[nikola-wan]

Great work on the 405x Emulator!

Here is the 4010 terminal GPLANET converted from PLOT10 format to R12 format shown in COARSE text and graphics mode, compared to the same file displayed in MIXED (coarse text and fine graphics) on the latest 405x emulator:



The 2x2 pixels on the COARSE image overlap and lose detail when the vectors are close. The MIXED mode image on the right is how it looks on the actual 4051, 4052 and 4054.