Hello^^
i have a problem with the app inventor when i upload pictures, such as one for the backround, it gets rly pixelated ? do you have an idea why , the pictures i import are big
Try resizing them to the width and height of your device, or use pictures that fit the ratio, or are close to the ratio of the desighner.
whats the optimal size for smartphones ?
The best picture resolution on smart phones is 640 by 320, and the best aspect ratio is 16:9. Aspect ratio is the relationship between the width and the height of your phone. For more on these subjects view the following links:
Dignited
Popular resolutions
More info
Device atlas
And app inventor questions
And app inventor questions-
(Setting a Background image which is looped rather than stretched)
(Keep image original ratio when inserting to a canvas)
(Image Size and Scaling)
its still a bad quality, but just in the app 
Also, load the .aia file and a screenshot of what's happening. Then we can get a better look at what is happening and provide better help.
the aia is unfortunatelly to private 
but its just the command set screen 1 backround image and im using a png in the size you told me but it still looks not rly good, but other picture i importet are nice its just the screen backroundimage
What's the resolution?
i changed it now to 640 x 320 but it was a lot bigger before
What is the aspect ratio of the device you are trying to display it on? look up the spec's for your phone or tablet, or go to about device in settings.
sry i dont understand the question? but it still looks very good on 640x320 on my pc its just bad when i use it in the app
You may be fighting a losing battle. See here:
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