Strange problem with transparent image rendering on iOS

[monx_develop]

I have UIImageView, which is used for showing image from resources. Image appears to be distorted. It is especially visible if you zoom the image in a graphics editor.
UIImageView size matches the size of the image.

currently used UIImageView parameters.

imgHeader.contentMode = UIViewContentModeCenter;
imgHeader.image = [UIImage imageNamed:@"logo.png"];
imgHeader.opaque = TRUE;
imgHeader.clearsContextBeforeDrawing = TRUE;

For UIImageView I tried changing parameters "opaque", "clearsContextBeforeDrawing" and "contentMode". Same result.


For resolving this issue I have also wrote classes AliasedLayer and AliasedImageView ( for antialiasing disabling the use of CGContextSetShouldAntialias and CGContextSetAllowsAntialiasing )
This is approximate code, there have been many attempts to change the code to correct image distortion. Same result.

@implementation AliasedLayer

-(id)init
{
	self = [super init];
	if (self) {
		img = [UIImage imageNamed:@"logo.png"];
	}
	return self;
}

-(void)drawInContext:(CGContextRef)context
{
	CGContextSetAllowsAntialiasing(context, false);
	CGContextSetShouldAntialias(context, false);
	CGContextDrawImage(context, CGRectMake(0., 0., 55., 18.), [img CGImage]);
}

- (void)renderInContext:(CGContextRef)ctx
{
	CGContextSetAllowsAntialiasing(ctx, false);
	CGContextSetShouldAntialias(ctx, false);
}

@end

@implementation AliasedImageView 


- (id)initWithFrame:(CGRect)frame{
    if (self = [super initWithFrame:frame]) {
        [self setClearsContextBeforeDrawing:YES];
	self.backgroundColor = [UIColor clearColor];
    }
    return self;
}


-(void)setImage:(UIImage *)img
{
	[image release];
	image = img;
	[image retain];
}

- (void)setNeedsDisplay{
    [self setNeedsDisplayInRect:self.frame];
}

-(void)dealloc
{
	[image release];
	[super dealloc];	
}

+(Class)layerClass
{
	return [AliasedLayer class]; 
}

- (void)drawRect:(CGRect)rect
{
	[super drawRect:rect];
	CGContextRef ctx = UIGraphicsGetCurrentContext();
	CGContextSetInterpolationQuality(ctx, kCGInterpolationHigh);
	CGContextSetAllowsAntialiasing(ctx, false);
	CGContextSetShouldAntialias(ctx, false);
	CGContextDrawImage(ctx, rect, [image CGImage]);
}

-(void)awakeFromNib
{
	CGContextRef ctx = UIGraphicsGetCurrentContext();
	CGContextSetAllowsAntialiasing(ctx, false);
	CGContextSetShouldAntialias(ctx, false);
	[super awakeFromNib];
}

@end

There have been attempts to dynamically load the image as well as using xib file. Same result - logo image is distorted.
Any ideas on what is causing this and how to fix it?

[nobre84]

How do you position the image on your view ? Be sure that the CGRect used as the image view's frame does not have fraction values as its origins or bounds. You can use CGRectIntegral() function to make sure they are good.