unable to view the grub splash screen

nkd · 12-09-2008, 03:57 AM

hi all I wish to display a personal image for the grub splash screen with the menu displayed on top of it.
I am using an original jpeg image which I have customised using the following command

Quote:

convert -depth 8 -color 14 -resize 640x480 original.jpg splash.xpm

and then I have zipped it using the following command to get a splash.xpm.gz file

Quote:

gzip splash.xpm

I have put the file in the /boot/grub dir and replaced he fedora8 infinity image in it with my image. However, on next bootup I see a black screen with the menu and on choosing the OS, the screen turns gray and then finally the GUI comes up as usual.
I tried to disable the hiddenmenu option on the grub.conf file as suggested by someone, but the result is still same....!
can someone help me out please.
thanks in advance
nishith

colucix · 12-10-2008, 01:34 PM

Are you sure that the resulting image has the requested features? For example convert -resize keeps the aspect-ratio of the original image and consider the specified width and height as maximum values. To force convert to use the exact size you have to put an exclamation mark after the size specification:

Code:

convert -depth 8 -colors 14 -resize 640x480! original.jpg splash.xpm

As alternative you can try Gimp (if available) to convert the image. Just scale the image to the requested size, then go to Image --> Mode --> Indexed and in the pop-up select "Generate Optimum Palette" and put 14 as the maximum number of colors. Then save as xpm and the trick is done.

I don't really know if this is the problem, but double check the newly created splash image before substitute the original one.

nkd · 12-11-2008, 08:24 AM

thanks
I tried it out , but that didnot solve the problem.
Actually when I open the image in Gimp, I see that the image has 255 colors and the moment I make it 14 colors, it looks strange.
Nevertheless, I scaled the image to 640x480 size, but it did not work and nothing showed up other than the gray screen. I guess it is due to the low number of colors. But the tutorials on grub splash screen suggest that only 14 color images will work.
Is there some way to use a photo taken with a digital camera (7 Mega Pixel)into a grub splash screen?

colucix · 12-11-2008, 08:58 AM

A digital camera photo loses a lot of quality with 14 colors. I tried to convert a 2 Mega Pixel photo and large areas of the images are grey and it appears dithered. The restriction to the image format are due to the VGA mode, which supports only 16 colors, two of which are reserved for text (black and white). I'm afraid you have to choose another image, at least to see if it works as a custom splash image using the same procedure.

nkd · 12-11-2008, 10:01 AM

yeah I saw the same explanation about the 14 + 2 color thing.
But this image is from the gnome art gallery and this image is supposed to be a grub splash screen created by someone. Don't they check these things ? I am sure they do and if it is a splash screen atleast the creator would have tried it out !
Also I can't remember it right but I read it somewhere that dithering can be switched off for the image using gimp when constructing the image in 14 colors. Will that help ?

any clues about these things ?
thanks in advance
nishith

colucix · 12-11-2008, 10:34 AM

Yes. I was thinking about the same: there should be a method in Gimp to reduce dithering, but I'm not an expert in image manipulation. I just tried the method described above, using Gimp, and the dithered image is displayed as grub splash. I'm sorry I cannot be of much help in this field.

Shadow_7 · 12-11-2008, 11:52 AM

You might try -scale instead of -resize with convert. You might also try putting -depth towards one of the last arguments. I'm not sure how order dependent convert is, but:

convert -depth 8 -colors 14 -resize 640x480! original.jpg splash.xpm

might work better as:

convert original.jpg -scale 640x480 -depth 8 -colors 14 splash.xpm

I've always had more luck with the gimp. And with 14 colors, the images generally look better if you convert it to greyscale, then dither it to 14 colors. You can of course mess with the various channels to make it red, green, blue, or any combination there of. But with a greyscale base, there's more common colors, all shades of grey. So the 14 color form of an image is less grainy.

nkd · 12-17-2008, 01:11 PM

Well Shadow_7, I have a question for you...
It seems like all the grub splash screens that are on the net are not usable, becoz they are not 14 colors to start with. They why would anyone create such a high color depth graphics and call it a splash screen when all that is usable is only 14 colors ?
I donot follow it at all ?
nishith

farslayer · 12-17-2008, 04:46 PM

Did you consider using the gimp to create/modify your splash image ?
http://ruslug.rutgers.edu/~mcgrof/grub-images/#1.0

Quote:

1.3.1 Only 14 colors... How do I do that?

To get GIMP to use only a 14 color palette, right click on your file and press ALT+I and put 14 where it says "Generate Optimal Palette:" on the top of the menu. If ALT+I doesn't get you there then right click on the image and go to:

Image-->Mode-->Indexed

Specify you want 14 colors and then if you want (*recommended*) select NO DITHERING. This will tell the gimp not to try to guess colors in between areas. It is also possible that you tell them gimp what colors you want in your 14-color pallete, I actually had to do this for one of my images and I replaced a dark color for a light one.

The GIMP ROCKS!

http://ubuntuforums.org/showthread.php?t=30341