UIImage save to file problem

Question

Hi,
I am new in iPhone development and I have a problem.
In my viewDidLoad method I have:
previewImage = [[UIImage alloc] initWithContentsOfFile:imagePath]];
self.imageView.image = self.previewImage;
where previewImage is UIImage type.
In View I have a slider to adjust brightness of that image.
- (IBAction) sliderValueChanged:(id) sender
self.previewImage = [ImageHelper brightness:self.previewImage level:self.slider.value];
self.imageView.image = self.previewImage;
+ (UIImage *) brightness:(UIImage *) image level:(float) level
int theheight = (int) image.size.height;
int thewidth = (int) image.size.width;
unsigned char *inbits = (unsigned char *)[ImageHelper bitmapFromImage:image];
unsigned char *outbits = (unsigned char *)malloc(theheight * thewidth * 4);
for (int y = 0; y < theheight; y++)
for (int x = 0; x < thewidth; x++)
float red = inbits[redOffset(x, y, thewidth)] + level;
float green = inbits[greenOffset(x, y, thewidth)] + level;
float blue = inbits[blueOffset(x, y, thewidth)] + level;
if (red > 255.0) red = 255.0;
if (green > 255.0) green = 255.0;
if (blue > 255.0) blue = 255.0;
if (red < 0) red = 1.0;
if (green < 0) green = 1.0;
if (blue < 0) blue = 1.0;
outbits[redOffset(x, y, thewidth)] = (unsigned char) red;
outbits[greenOffset(x, y, thewidth)] = (unsigned char) green;
outbits[blueOffset(x, y, thewidth)] = (unsigned char) blue;
free(inbits);
return [ImageHelper imageWithBits:outbits withSize:image.size];
Methods "bitmapFromImage" and "imageWithBits" are from "iPhone Developer's Cookbook" book.
When I click a button I'd like to save changed image to file as jpeg. The problem is, that I always get a white image with size of imageview. Have somebody an idea what do i wrong?
For saving I use:
[UIImageJPEGRepresentation(self.previewImage, 1.0f) writeToFile:imagePath atomically:YES];
Thanks for any help.

Answer 1

Switch to Grid view - anything you do in Grid view will always apply to all selected images.