Picture scaling - memory issues

[jonck]

Hi,
In my app people can load a picture, which I then show in a scaled down
version. To do the scaling I follow the sample code as shown here:
http://javaalmanac.com/egs/java.awt.image/CreateTxImage.html

All this works fine, though sometimes if a user loads in a very large
pictuer I get an OutOfMemory error. Now ideally what I would like to do
is test before the picture is loaded whether there is enough memory
available to do the operation. In order to do that I would need to get
an idea of how much memory will be needed to do the scaling.
Does anyone know what (roughly) the proportion is of memory used to the
size and depth of the picture?

Thanks, Jonck

 

[Thomas Weidenfeller]

All this works fine, though sometimes if a user loads in a very large
pictuer I get an OutOfMemory error. Now ideally what I would like to do
is test before the picture is loaded whether there is enough memory
available to do the operation.

This is in general unpredictable. During the (small) time between your
test for memory and the loading of the image some other process might
have gotten the memory. So even if your test tells you that there is
enough memory, you application might fail later.

/Thomas

 

[Boudewijn Dijkstra]

Hi,
In my app people can load a picture, which I then show in a scaled down
version. To do the scaling I follow the sample code as shown here:
http://javaalmanac.com/egs/java.awt.image/CreateTxImage.html

All this works fine, though sometimes if a user loads in a very large
pictuer I get an OutOfMemory error.

There are algorithms that don't have to load the entire image before scaling
begins.

Now ideally what I would like to do
is test before the picture is loaded whether there is enough memory
available to do the operation. In order to do that I would need to get
an idea of how much memory will be needed to do the scaling.
Does anyone know what (roughly) the proportion is of memory used to the
size and depth of the picture?

1

 

[Boudewijn Dijkstra]

There are algorithms that don't have to load the entire image before scaling
begins.


1

Unless of course you have the image in video memory, in which case the rough
proportion is 0.