Comments on: Example 15-8: Adjusting Image Brightness

By: Lpcambra

Lpcambra — Mon, 06 Feb 2012 14:36:00 +0000

Hello, I downloaded the example and it worked, also it seems i wasn’t saving in a separate folder all of the different codes and it was creating problems, all works now.
Thank You, for the time Mr. Shiffman.

By: Anonymous

Anonymous — Thu, 02 Feb 2012 18:25:00 +0000

sorry, i’d need to know more of the error. did you make sure you have the image file in your data folder? try downloading the example and run that directly rather than re-typing it.

By: Lpcambra

Lpcambra — Wed, 01 Feb 2012 18:04:00 +0000

Hi, Mr.Shiffman

Just tried to do the same code as above, but i’m gettin the same error over and over…

” Could not find a method to load lomotomocopy
Exception in thread “Animation Thread” java.lang.NullPointerException”

I’m running it on a windows7 64, on the Processing version 1.5.1

i’m very “noob” at this…

By: Michael

Michael — Sun, 18 Sep 2011 22:41:00 +0000

Pls. disregard the post below, after println’ing adjustBrightness, I now understand we’re adjusting the entire image from dark to light, rather than just brightening what exists.

By: Michael

Michael — Sun, 18 Sep 2011 22:29:00 +0000

I understand why we use adjustBrightness, but I’m unclear as to how we calculated it; specifically why we multiply mouseX by float. Also, why not use mouseX as-is? Why create a fraction then on top of that figure in a multiplier (0–8)? Thanks Dan!

By: Anonymous

Anonymous — Mon, 23 May 2011 17:57:00 +0000

There is an ‘r’ for every single pixel (640 *480!) so you are printing 307,200 lines every time through draw, that’s too much for the message console to handle. Try just printing out the center value or something.

if (x == 100 && y == 100) {
println(r);
}

By: Anonymous

Anonymous — Mon, 23 May 2011 17:57:00 +0000

It’s likely your image file isn’t the same resolution as your Processing sketch. i.e. if you have

size(600,400);

your image needs to also be 600×400 (for this example to run). Otherwise, you’d have to alter the math and use a different “loc” for the Processing window and the image pixels.

By: Slopeavery

Slopeavery — Sun, 22 May 2011 16:03:00 +0000

I tried to view the value for “r” using println(r) it freezes the program, I’m not sure why.

When I make “r” a global variable I see numbers close to what I expect if a place the code after updatePixels();

updatePixels();
//println(“r is ” + r);

If I put it in the body of the code it stops working, don’t get that either.

Thanks for the book! I’m enjoying it.

By: Daniel Shiffman

Daniel Shiffman — Wed, 22 Dec 2010 19:02:20 +0000

It’s likely your image file isn’t the same resolution as your Processing sketch. i.e. if you have

size(600,400);

your image needs to also be 600×400 (for this example to run). Otherwise, you’d have to alter the math and use a different “loc” for the Processing window and the image pixels.

By: Matthew M

Matthew M — Tue, 21 Dec 2010 05:22:34 +0000

Thanks for all of the examples. I keep running into a ArrayIndexOutOfBoundsException: 40320 error when I try and run this code example. I originally just tried to adapt the previous code to enhance my knowledge, but when that failed I ran this code (cut and paste) but added my own test image. I was able to load and use a test image with prior code examples.

Any suggestions? I am using Processing 1.2.1 on a Mac.

The line it highlights is ” pixels[loc] = c;”