loadImage() in javascript

Jeff Tsuk..

in Processing with Other Languages • 1 month ago

So i'm trying to find out the upper limit to the loadImage() function in javascript. Anyone have any advice for file sizes and etc? Using the trycatch is not a great idea, since you want the images to finish buffering up before displaying.

So is does the program need to sleep for a certain amount of time to determine if the load is successful?

Replies(7)

Jeff Tsuk..

Re: loadImage() in javascript

1 month ago

Because switching between java / javascript produces different images depending on where the camera() line is called. And whether you can image() a picture.

dimkir

Re: loadImage() in javascript

1 month ago

So i'm trying to find out the upper limit to the loadImage() function in javascript

I wonder what kind of job are you trying to accomplish? Usually loading big enourmous images in JavaScript as one big image is a bad idea.

If you look at other web-based solutions like

http://www.harlem-13-gigapixels.com/

you can see that despite as the backend they have a HUGE gigapixel images, they always load only a bit of it. Otherwise user would have to wait for 15 minutes to see how his computer crashes with out of memory error.

So your best solution in case you need to work with big images: to slice them and prepare "zoomed out" versions.

As to maximum meory capacty, my Chrome managed to load image below (10000px x 3000px) around 30Megapixels,

http://sadelserradilmener.files.wordpress.com/2010/10/louvre_museum_pyramid.jpg

And if you really want to push your luck here's 230Megapixel image

http://commons.wikimedia.org/wiki/File:Salt_Lake_City_panoramic_map.jpg (just click on the image)

or here's direct link to the 230Megapixel (that would result in PImage of dimensions around 1Gb or more)

http://upload.wikimedia.org/wikipedia/commons/1/1a/Salt_Lake_City_panoramic_map.jpg

EDIT:

you can see that even whilst only having 1/4 of the image Chrome memory consumption for the tab with the image is alredy 1GB

dimkir

Re: loadImage() in javascript

1 month ago

HTH

Or here's another example of using High-definition images.

http://www.haltadefinizione.com/en/component/content/article.html?id=156

Jeff Tsuk..

Re: loadImage() in javascript

1 month ago

No i know what memory management is. If it was straight javascript, that'd be ok,but the issue i have is something like this:

From what i recall of a sketch ....

/@pj etc.etc.... /

PImage a;

void setup(){

try{

a=loadImage("./data/afile.jpg");

}catch(Exception e){

println("image not loaded");

}

boolean testLoaded(){

if(a==null){

return false;

}

return true;

}

void draw{

if(testLoaded()){

println("tested");

}

else{

println("not test");

}

background(0);

camera(0,0,c++,0,0,0,0,1,0); // works in javascript

fill(123);stroke(255);

box(20);

image(a,0,0);

//camera(0,0,c++,0,0,0,0,1,0); // the box appears at top left corner of the sketch but in java works as expected.

}

A nullpointerexception is not called, meaning it's loaded, but the image never appears. Switching to java mode, the image appears. Also the placement of the camera invocation has an effect on the the scene. Are there any gotchas to the use of the processing javascript? Like exported jpgs etc from certain applications ? I'm using gimp... etc? Also for javascript processing has a tendency to fail silently, ie. nothing on the console. You have to insert debug statements everywhere just to pinpoint the error. The java version works fine though.

dimkir

Re: Re: loadImage() in javascript

1 month ago

.This code will never throw any exceptions. loadImage() returns null or valid PImage, but never throws exceptions.

try{

a=loadImage("./data/afile.jpg");

}catch(Exception e){

println("image not loaded");

}

Jeff Tsuk..

Re: loadImage() in javascript

1 month ago

Ha!

Turns out the javascript version of processing, does not seem to load from the "./data" part of the sketch folder. The java version loads from both.

A pebkac moment if there ever was one.

Jeff Tsuk..

Re: loadImage() in javascript

1 month ago

" If the file is not available or an error occurs, null will be returned and an error message will be printed to the console. The error message does not halt the program, however the null value may cause a NullPointerException if your code does not check whether the value returned is null." -- from the writeup

You're right. It doesn't throw anything. It's only up to the point where the null value is accessed that the program does. Well ....

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