View Full Version : Screen Jaeger, a bitplanes ripper...and something more

18th January 2016, 01:05

the matter of this thread is more of a review of a screen ripper: moderators should move this thread in a more appropriate section, if needed!

Tonight i wish to teach you how to made funny icons of your preferred Amiga games and demos. Just choose the image that you wish to have on the workbench icon from what the intro of the game (or the game itself) offer, or play and take a look at what content of a demo is funny to be part of the imagery of an icon.
The theory is that: during a game or demo, if you reset the machine, the chip memory maintain 99% of the data (pure data and code) stored on it at the time of the interruption; but at the reboot, to preserve the major amount possible of content, do not start the workbench! In other words, do all the possible to limit the consumption of chip memory at the next reboot: in this way, most data and code will be preserved.
This little tutorial speak about graphic data stored into chipram (memory used by the custom chips of the classic Amiga models), organized as graphics bitmap named bitplanes.
The most requested memory area used by games and, less, by demos, are the first 512Kb; then follow the remainder (other 512Kb on the models equipped with 1Mb of chip ram, or 1.5Mb on the models equipped with 2Mb of chip ram).

To complete this tutorial we are in needed of some tools:
- a bitplanes ripper, that act as memory viewer (i have chose screen_jaeger, that do not support AGA);
- another Hex/ASCII memory viewer, like MonAm from HiSoft;
- a graphics program like DeluxePaint;
- a graphics tool for icons, like Iconian.

Well, at this point we can start to play the game/demo and then, ready to reset the machine when the desired picture is displayed...

Notation: a picture (or frame, if part of an animation), can be made of graphics data stored into bitplanes (what we are looking for), or copper (a co-processor) instructions (what we are not looking for, because this is code that generate signals for the video encoder, Denise or Lisa, and not graphic data into chip ram) or sprites and bobs (that are in chip ram as graphics data, but for sure in a completely different location respect the background and other graphics elements that compose the image).
Another thing, avoid interleaved BitMap, because i have not found a valid graphics ripper that support it (but they are valid image data into chip memory).

For this tutorial i have chose one of my favourite games (that i play actually, sometimes), Puggsy: it was, with original floppy disc and manual, onto my first A1200, bought many years ago.

So, let play the game on my A3000D! Here the sequence


For the icon that i will do, i have chose the two frames of the two animations (photo n.4 and n.5).
I restart the game and reset the machine at the selected point of the first animation. Then, i reboot the amiga without startup-sequence and let start the bitplanes ripper screen_jaeger.

Notation: you need to know about the graphics resolutions that Amiga can with original chip set, about the palette of colors and the relation between depth (number of bitplanes that compose an image) and number of colors.

With screen_jaeger, we start to look inside the chip memory, to find something similar to the frame that we have chose as image to save and to convert as icon...


...an image already viewed...


18th January 2016, 01:16
Take a look at this sequence


this is the last frame of the animation, that was stored into the chip ram at the time i have rebooted the machine: they are the different bitplanes (stored sequentially) that compose the (last) frame. Let compose them in an unique picture...


and save it onto the harddisk (or floppy disk).
About the resolution of the picture, screen_jaeger help you to find the right one. But the original palette of colors is missing! You can arrange a new one similar to the original when you play with this picture on DPaint, or try to close screen_jaeger, to launch MonAm and start to search for the code inside chip memory, that retain the information of the colors palette of this frame.


I have chose the first option, take a look...



18th January 2016, 01:29
...and the final touch...


then, clipped out a part of the image as a brush, the icon will be created with the program iconian


Same procedure for the second picture chose to compose the new icon


That's all, have fun with it!