Random Screensaver Image

[frostschutz]

try delay=0.1 0.1 0.1 0.1 0.1

the default delay was more geared to the logread method, which no longer works

I also have an idea how to make this setup process easier in the future. I just have to find the time (and motivation) to actually implement it. Basically the scan line right now is a shell script, but if I re-write it in C it should be fast enough to detect the correct offsets and signatures automatically... that's the theory anyway

[Symptym]

Originally Posted by frostschutz

try delay=0.1 0.1 0.1 0.1 0.1

Sadly that delay is too short but delay=0.1 0.1 0.1 0.2 0.4 nearly seems to do the job.

it's a little stuttery but any longer or shorter was leaving 'Easons' on the screen. I think different sets of intervals for nearly the same amount of time might help if it works the way I think it does.

might experiment a bit tomorrow starting with a 0.2 0.2 0.2 0.2 delay.

[frostschutz]

What's "easons"? If that's Sleeping/Poweroff in any language, and that string appears after the mod already displayed an image, the signature is wrong.

[Symptym]

Easons is a chain of bookshops.

they're also kobo resellers and any kobo e-reader bought from them has its own splash-screens, screensavers and power off screens with their name on it.

when one of those enters sleep mode you see 'sleeping' for maybe half a second at most before its replaced with a white screen saying 'Kobo | Eason' to represent where it was bought. The power off screen is black with a white 'Eason' on it.

changing the affiliates file from 'Eason' to 'Kobo' got rid of those splash screens but also stopped the screensaver from appearing at all somehow. The built in book cover screensaver still worked fine once it was reactivated.

I turned on debugging mode again but I was still getting exactly the same signatures with the same offset, I tried a few other offsets and signatures but still no luck.

changing the affiliates file back had the screensavers working perfectly again but it seems it will occasionally show the screensaver, Easons screensaver and then either a different screensaver image or the Easons one again as it sleeps or turns off.

I tried having the scan line read the Easons screensavers but in those cases it never even started to activate so I have to assume it shows up to late to output the image after it reads it or that it cant scan for some reason.

[frostschutz]

Ooh. I never tested with affiliate images, sorry. Those would even break the idea I had to make the setup simpler, I guess... I just have affiliate=kobo

[Symptym]

having had the chance to test on a friends Aura HD 3.18.0 in English that is direct from Kobo I can say that my delays, offsets and patterns worked perfectly every time.

however, changing the affiliate on mine to Kobo did, as I mentioned, somehow stop the screensavers from working at all.

I didn't try setting his affiliate=Eason because I wasn't sure that the affiliate image would be built in and wouldn't cause some sort of boot issue due to a missing resource so I've no clue how that changes things.

I wasn't experimenting with any different delays yet today but I have noticed that the simpler the screensaver image the more likely it is that the affiliate image overwrites it (your default KittenTree2 image is always over written) whereas large 1.5-1.9MB images will always show if they are selected (eg. this or this) so I'm assuming that I have to adjust the delays further to account for the affiliate screensaver and the size of the file.

also, and annoyingly, on my friends the screensaver appears when it times out and sleeps/turns off so that's fine but on mine it hits 15 mins (how I noticed it), or the 1 min I was using to test, and it goes right to the Easons one without mine even flickering.

*Edit:* A bit of further testing shows that a copy of the second image linked there with the colours reversed to be mostly white is also generally either fully or partially overwritten so it may be that it takes more time to parse/draw the image. Which doesn't explain why it works perfectly fine on his every time unless the affiliate screensavers are written using a similar method to yours.

*Edit 2:* I also noticed that when his times out the regular 'Sleeping' or 'Power Off' show up whereas on mine, when it automatically sleeps, it goes directly to the Easons screensaver without displaying a sleep message... Which I suppose neatly explains why the screensaver doesn't work in those cases.

[frostschutz]

I'll see when I can find the time to test with affiliate image.

When you debug=1 does the scanline not show up on top of the affiliate image?

[Jorg3]

Worked perfectly on my Kobo Glo HD running 3.18.0 in English using:

offset=145
standby=0080aa5961da66a80050e705d3782e65
poweroff=434583f85d17b2480ddc32087676baf7

Thanks a lot for the mod Frostschutz!!

[lampman314]

I do not remember why I decided to try my luck and see if anyone online figured out how to make custom screensavers for the kobo e-readers but I am glad I did.
I almost did not want to get a used Aura HD for a low price because this feature did not exist and there were no hacks at the time.
many thanks frostschutz,
your procedure was successful on my Aura HD with firmware 3.18.0.

I used the scanline method of course and here are my results that I got with the debug:

offset=145
standby=e3b115f0c3e42bcef1afcbbb4f10e6da
poweroff=62aed5baa23b6f925d79d836b221ebf5

--------------------------------------------------------------------------------------

I hope to contribute something in regards to creating optimal images for use on at least the kobo Aura HD. I do not know which other devices share identical screen characteristics.
I used to have a kindle 3rd gen. Before it broke I almost perfected the art of creating wallpaper files. I made a custom PNG profile in photoshop to export as a greyscale with 8 levels, and I set each level manually once based on the kindles 8 level screen.

the Aura HD screen is listed as having 16 levels on wikipedia. I loaded a gradient from white to black (which I assume photoshop makes linear) as the only image and noticed that the kobo does not dither the image, but instead has a hard sampling a.k.a. quantization technique. I notice very equal spacing between each sample. If the original gradient is linear than the quantization is linear.
I applied a 2 different 16 level ditherings to the gradient with photoshop and loaded those images to inspect them.
one of the ditherings photoshop used its own algorithm.
for the other one, I manually chose the greys from 8-248 in steps of 16, so: {8,24,32,...,232,248}
I attached files for all of these examples.
my conclusion is that a linear levels for dithering is not ideal. there are uneven bands on the Aura HDs screen but not on my computer monitors from both dithered images.
That being said any type of dithering gives a huge improvement in the perceived image quality.

---------------------------------------------------------------------------

I will also share show I save my images.
I only use photoshop, perhaps there is an equivalent procedure in GIMP, I do not know.
-first I get a high res image of course,
-crop it to 3:4 ratio
-(edit) select auto contrast or use curves manually to get some clipping into the black and white
-sharpen if needed
-if it's a color image, I go to: image > adjustments > black and white. then I play with the presets until I find something I like and then maybe tweak it from there.
(this control can give significantly better results than simply desaturating)
-resize to 1080x1440
-file > save for web. then choose PNG-8, 16 colors, adaptive mapping, 100% dither.
-save

I have included a screenshot of some dithering comparisons
top left is the original image
top right is 100% dithered with my 16 level profile
bottom left is 100% dithered with an auto 16 level profile
bottom right is 0% dithered with an auto 16 level profile (somewhat how the aura hd would show the image itself based on the gradient test)
my profile does look better on the PC screen but if the results of the gradient test repeat then it might not translate to a better image on the aura. but the difference is negligible in a more detailed area anyway.


for me the hardest part is choosing what images to use. I have made 4 so far and I can share a live folder if anyone wants.

hows that for a first post?

[Symptym]

Originally Posted by frostschutz

I'll see when I can find the time to test with affiliate image. When you debug=1 does the
scanline not show up on top of the affiliate image?

Sorry for the delay. Its been an odd few weeks but it did indeed show up once I got around to trying it.

Offsets were left the same as previously (delay=0.1 0.1 0.1 0.2 0.4) because I haven't had the time to experiment with them though. They could be better but I'll have to work on that.

So, for Aura HD 3.18.0 in English with the 'Eason' affiliate images these were the working offset and signatures;

offset=730
standby=6377b6db5e94ace199c5376faa047319
poweroff=2e22f76fe5a0e23a1aa32a90f2f504f8

Originally Posted by lampman314

I will also share show I save my images.[...]
I have made 4 so far and I can share a live folder if anyone
wants.
hows that for a first post?

It's a damned good first post and that looks like a lot more detail work than my own images got.

I opened them up in paint.net, clicked 'Adjustments -> Black And White' which gave me an image that looked fine. Then I had a look at the sizing, decided what was important in the image and either resized or cropped then resized so that I had something about the right size for the screen.

If the ratio wasn't right I increased the canvas size with the current image at the center and then picked a colour for the new canvas around the image.

As for the live folder; Yes please!

Extra images would always be welcome.

*Edit:* Not sure if anyone else sees it but if they do and know how to get rid of that half screen of empty space at the end of my post please do tell me.

[lampman314]

Originally Posted by Symptym

...
I opened them up in paint.net, clicked 'Adjustments -> Black And White' which gave me an image that looked fine. Then I had a look at the sizing, decided what was important in the image and either resized or cropped then resized so that I had something about the right size for the screen.

If the ratio wasn't right I increased the canvas size with the current image at the center and then picked a colour for the new canvas around the image.

As for the live folder; Yes please!

Extra images would always be welcome.
...

Does the black and white option have a way to adjust how bright each each color would be in the final image? because for some pictures with lots of colors it makes a world of difference. When I get home I will make a gif animation of one particularly striking example I found recently.
also your cropping method sounds a bit lengthy, in photoshop I set the ratio to 3:4 and put the vertical rectangle around what I want. press enter and that's it, the ratio is always perfect. I resize at the very end right before saving. I think this will maximize output quality.
I skip many images that don't have a good 3:4 crop in them, or if I have to increase the resolution by more than 25% to get to fit 1080x1440.

When you save as a B&W PNG do you have dithering options? I think that this is the most important part.

perhaps in a few days I will try out paint.net and GIMP and try to develop a similar procedure.

Here is my folder of screensavers I made; 23 so far (some are maybe semi NSFW)
https://mega.nz/#F!UtgCiRoA!cZPkqxrDCgHXnRLkJi8Cgg
Its just paintings/photos that I really like and have the appropriate format/resolution that I am looking for. It should update automatically as I add more.

I only saw about 7 of them in my screen and they all looked nice except for the castle on the hill which was a little flat.

they are all 1080x1440. If you want to use them in a lower resolution device you need to re-dither the image after resizing or you will probably get serious banding as any interpolation technique other than nearest-neighbor will un-dither the image. and I am not sure if nearest neighbor will look very good anyway.

[lhommealenvers]

Hi.

So this is the first time I ever install anything on my e-reader except for e-books. My 3.18.0 H2O is configured in French so I had to deal with finding the right signatures and had to go the long way because th offset value of 105 did not work for me (I have it set at 155 now).

Here they are for the French people around :

offset=155
standby=6b57f9535633b7624ddb9b99a09a7fd4
poweroff=4b05d0e14f92a421f89c07f979824f24

There is one thing I discovered while debugging : the value f400e0d8bdc587d96e9d14fcd584144c appears in the log no matter the value of the offset ; my conclusion is that this value probably appears with a completely blank line. Also I noticed some of you had this value in your settings as well. So if you get this value it's probably a wrong one.

Now since I installed this mod and set it up in scanline I'm having a recurring issue with the reader only displaying the "Sleeping" text. I guess it's because of the delay values. I'd agree to do some more exploration, but can I get more explanations as to how they affect behaviour ? Are the values delays between each line scanning ? In which unit ? Can one put fewer or more values in this field ?

I am trying Symptym's values and they seem to work. I had Fnac affiliation but I had set it back to affiliate=kobo some time ago.



Edit : I found and processed a few pictures. As lampman did post his folder I am going to do the same here : https://imgur.com/a/FcNXr

[lampman314]

Originally Posted by lhommealenvers

Hi.
...
Edit : I found and processed a few pictures. As lampman did post his folder I am going to do the same here : https://imgur.com/a/FcNXr

I checked out a few of those images and some are not black and white and are not PNG. I do not know how strict the Kobo is about this but I prefer to have full control.

I wrote out a long and detailed post but I lost it when the forum logged me out when I clicked preview.

I included 2 attachments, one is an animated gif showing the power of the black and white converter in photoshop. you can read the preset on the left. there is default which is mediocre, a few awful ones and a few good ones.
the other is the original color image, credit goes to an anonymous photographer.

My experience with Paint.net;
you can set an aspect ratio to select with, make a selection and crop to selection. It is possible to have control over the black and white conversion by manually adjusting curves and brightness/contrast before selecting black and white. and of course you can resize.
there is one fatal drawback to Paint.net; when you save as a PNG, there is only "bit depth" to choose from. the lowest number of 8 is much too high. a 16 value grayscale is 4 bits. I would not use paint.net because of this limitation alone. It can work for very contrasty and sharp images like some of the ones lhommealenvers has in his folder.

The GIMP does have what I am looking for and I will list steps for conversion here:
* Play with the color curves and brightness/contrast. my method: the colors I want to be light, I make light. Same for dark.
* make other adjustments you wish to
* colors -> desaturate, and I use the luminosity setting because of my previous curves adjustments
* resize to 1440x1920, or whatever resolution you have.
after you adjusted everything you wanted do this step last:
* image -> mode -> indexed

*generate optimum palette: 16 colors (maybe less for older models? I know the kindle 3rd gen uses 8 levels)
(IMO the most important part: )
* color dithering: choose from any of the Floyd-Steinbergs. I do not see a difference in grayscale. 'Positioned' looks similar to 'patterned' in photoshop. this might work better for images with very fine (near pixel sized) noise that you want to keep

* save your image

the biggest benefit photoshop brings is how easy the black and white conversion is. it combines the many seperate steps that you need to do in paint.net and GIMP, if you really care about which colors appear bright in your final image. I think sometimes it really matters, as I hope you can see from my attachments. also photoshop has really easy and quick previews of the indexing and dithering, which it also forces to be a last step.

[Grifter357]

Hello Everyone,

I finally got the scanline mode to work for my Kobo Aura H2O with the 3.19.5761 firmware. Sleep and Power-off mode both use random screensavers from the same pool. Putting files in the "off" sub-directory (specific screensavers for power-off mode) does not work.

Many thanks for the mod Frostschutz!!

Here are my settings:

eBook Reader: Kobo Aura H2O (international)
Firmware: 3.19.5761
Language: English

offset=145
standby=e3b115f0c3e42bcef1afcbbb4f10e6da
poweroff=bdec713d2c1a2b9ebc9db6dead7a788f

Best Regards!


P.S.

Curiously, my settings are almost similar to the results of lampman314 for the Aura HD (3.18 firmware):

offset=145
standby=e3b115f0c3e42bcef1afcbbb4f10e6da
poweroff=62aed5baa23b6f925d79d836b221ebf5

I checked my scanline.txt file and I also found instances of the "62aed5baa23b6f925d79d836b221ebf5" values... Strange...

[waqar]

Hi frostschutz

I have checked it on Kobo Glo HD running firmware 3.19.5761. It works great. although i see quite alot of screen flickering while it goes to sleep or wakeup. even when using "sketch". Is there some way i can reduce this flickering. It seems the reason for it are the delays that i have used. I will be sure to share the configurations I used later today.


TC All