PRS-950 Proper Sizing for 950 Wallpapers = 800 X 480 (or any other 5:3 ratio)

[tommylander]

I thought I'd post this in case anybody else was having trouble getting their screen wallpaper images to show up properly in standby on the 950.

I was using 800 X 600 images (like on the 650) at first, but then I realized the pictures were getting stretched out on standby and not coming out the way I wanted them to.

So I tried to find the proper sizing for the larger 950 screen and couldn't find anything, and then I had a flashback to geometry class and decided to try to figure it out myself.

Namely, I remembered the Pythagorean Theorem for right triangles: a2 (squared) + b2 = c2.

And I knew the 650 screen fit images with the ratio 800 X 600, and also the screen measured 6 inches if you drew a diagonal line from one corner to the other.

So I used the info to come up with these equations:

1) a2 + b2 = 36 (6 squared)

2) a = 3b/4 (b is the longer vertical side of the screen; 600/800=3/4)

Then using replacement, I came up with this:

(3b/4)2 + b2 = 36.

--> 9b2/16 + b2 = 36

--> 9b2/16 = 36 - b2

--> 9b2 = 576 - 16b2

--> 25b2 = 576

--> b2 = 23 (I rounded off a tiny bit here)

Going back to the original a2 + b2 = 36, I could now calculate that a2 = the square root of 13, which comes out to be almost exactly 3.6.

This gives me the length of the shorter horizontal length of the 650 screen, which is equal to the horizontal length of the 950 screen. Now I had to use this info to get the length of the longer vertical length of the 950 screen:

(3.6)2 + b2 = 49 (as the diagonal length of the 950 screen is 7 inches, not 6)

--> 13 + b2 = 49

--> b2 = 36

--> b = 6

Now I knew that the dimensions of the 950 screen was 6 inches (vertical) by 3.6 inches (horizontal). Voila, that gave me a 5:3 ratio for the two lengths, which meant that any wallpaper images for the 950 screen also needed to have the same 5:3 ratio, as in 800X480 or 1000X600.

So I resized and cropped my wallpaper images to fit the 5:3 dimensions, and they now work perfectly.

Anyhow, I wanted to post this geeky thread to show that some things you learned in school DO end up being useful in adulthood

[natasha_fawn]

Yay, algebra! The dimensions used in the standby screens preloaded on the reader are 600x991, which is 5:3. I've found that 1280x800 works out quite well (it's not exact, but close enough that it would be very difficult to tell), and it is a common size for wide-screen desktop images and others.

So if you're looking for images you don't have to crop or resize, there are a few options. What I've done is to go to Google images advanced search, enter something general that I'm looking for, and then use the "Exact Size" filter. I tried 600x991 (and vice versa) at first, but there are very few results because it's not a common size. 1200x800 or 1200x768 get a lot of results, and their reverses for portrait get quite a few depending on your search terms. Or if you're not getting something you like, use your math skills and enter any 5:3 ratio into the exact size filter and see what you get. (Pixel counts greater or equal to 600x991 will get you better looking pictures, anything below 600x991 risks the image being pixelated.)

[wallcraft]

The actual screen size is 600 x 1024, which has become popular in netbooks but does not have a simple width:height ratio. It is close to 3:5. If the preloaded images are 600x991, perhaps they don't completely fill the screen.

[ayryq]

I did some tests with some quickly GIMPed JPGs. The 600x991 image is definitely being scaled to fit the screen, and the 600x1024 image is displayed pixel-for-pixel. If you're (as I am) cropping JPGs of your family for wallpaper, go for 600x1024. Beats me why Sony used the smaller resolution (true on the 350 I had briefly too).

EDIT: adding the jpgs I used for test.

[ayryq]

I did some more testing and it appears that the Reader is scaling proportionally. The 600x991 was being scaled up to 620x1024 to fill the screen, and then the extra twenty pixels were cropped (ten from each side).

Eric

[ayryq]

By the way, I'd like to recommend a handy tool I discovered when cropping and resizing pictures for one of those LCD picture frames. It's called "Drag-n-crop" and it's free.

You put all the pictures you're planning to use into a directory. Fire up Drag-n-crop, tell it the dimensions you need, and the directory of pictures. It goes through quickly, allowing you to crop only to the dimensions specified, and saves the altered files.

Only available for windows and mac, at http://www.harveyosity.org/dragncrop/

...allowing you to take a very large number of images and reformat them all to precisely fit a given output device, in a short period of time while (and this is what sets it apart from similar tools) allowing the user to easily customize cropping for each image.

It shows you a picture, you drag a box which is constrained to the ratio of 600x1024; it saves the file and shows you the next one. Couldn't be simpler (unless it worked in Linux!)

[flexnib]

Thank you all! Very helpful indeed.