[Galaxy S III Mini General] tys0n:
[i8190][HOW-TO]-[param-mod]-[BOOTLOGO]

!!Disclaimer!!​

You will be responsible for your own work. Don't blame me for anything that might go wrong with your phone.

I've done this and it worked just fine, but then again...i'm not you :)

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Ref. and research:

What is param.lfs, and why do we have it?

Param.lfs is needed for the bootloader to go on with the boot. Inside your phone there's a /lfs-partition which works as a image cache for the bootloader. It contains the bootimages, charging, warning, etc etc.

If image is not there it will fail to boot.

After extracting all images in param.lfs with "param-tools" I noticed there was a difference from the param folder in the phone.

One picture was missing in param.lfs.

In "/mnt/.lfs" there is a "logo.jpg" which is nowhere to be found in param.lfs.

View attachment 2272802

As you see in the zip, all bootimages are very low-res (96X160) but that "logo.jpg" in device is 480X800 so I realized that it must be created inside device on first boot after flash, somehow rendered from the two low-res images inside param.lfs.

I asked a few friends with L/N-models about their logo.jpg and they confirmed that it was there, but of course with the bootimage for their L/N-model.

I copied the "logo.jpg" from device and dd'd the param-partition from device and started searching for that "logo.jpg"...

This is where my work start.

Ok so we all got it, but it's different for all models, right. What if I change the 640X480 "logo.jpg" from the dd'd param instead of edit the small 90X160 model-specific images that other how-to's and mods suggested, which would have to be done for all models.... A total of six images!

This way, edit one 640X480 "logo.jpg" should make it work on all models, and it did!

So, how do we look whats inside param, and what do we look for?

We have to use a hexeditor to be able to do anything. I used HxD. Other editors work as well, but they have different options for copy/paste etc.

A *.jpg in hex always starts with "FF D8" and ends with "FF D9" (Ref.)

How to do it..​

First you'll have to make a "logo.jpg". Choose your tools for that as it will not be covered in this how-to.

Save your created picture as logo.jpg, 480X800, NOT BIGGER THAN 64673bytes. (176241 in octal numbers)

This is only safe with this specific param.(Attached at the buttom of post) Other params may have the picture in different offset.

Open attached param.lfs in HxD.

View attachment 2272806

We will work with octal values.

Choose edit/select block.

Start:02464000 --> End: 02662240 (The lenght should now be 176241)

View attachment 2272807

View attachment 2272808Start of block

View attachment 2272809End of block

Go to File/new. A new empty tab will open.

With the new tab in front -->Edit/insert bytes.

View attachment 2272813

Bytecount must be same as the lenght-value from the block we marked in original param.lfs (176241)

You'll get a notification, just klick yes.

Now we have an empty block in the same lenght as the picture we want to change.

Open your 480X800 logo.jpg in HxD. Right klick/select all, then copy.

Go back to the empty file we made, right klick/paste write. (make sure you runnung HxB in overwrite mode.)

View attachment 2272814

Save it as logo.jpg.

We should now have a new logo.jpg with exact the same lenght as the one in param.lfs.

Copy it the same way we did before, but now you paste write it into the marked space in param.lfs.

Save it as param.lfs and make sure its not bigger than original param.lfs.

You're done!

Now you can open (not unzip) the attached cwm-zip and overwrite the param.lfs in there, and flash in your custom recovery.

The one inside is an inverted i8190 stock image. Black on white background.

View attachment 2272795

Some of the params I've made so far. Here you'll also find odin flashable params if anything goes wrong. Download mode will still be accessable.

I believe this should work for other Samsung devices as well, with their specific param, and the right offsets for that param.

Thanks to [MENTION=4021423]ketut.kumajaya[/MENTION] for param-tools, [MENTION=2942074]DemonWav[/MENTION] for reference for where to start.