Have following code for rotation:
CGFloat angleInRadians = angle * M_PI/180.0;
CGFloat width = CGImageGetWidth(imgRef);
CGFloat height = CGImageGetHeight(imgRef);
CGRect imgRect = CGRectMake(width, height, width, height);
CGAffineTransform transform = CGAffineTransformMakeRotation(angleInRadians);
CGRect rotatedRect = CGRectApplyAffineTransform(imgRect, transform);
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef bmContext = CGBitmapContextCreate(NULL,
rotatedRect.size.width,
rotatedRect.size.height,
8,
0,
colorSpace,
(CGBitmapInfo)kCGImageAlphaPremultipliedFirst);
CGContextSetAllowsAntialiasing(bmContext, true);
CGContextSetShouldAntialias(bmContext, true);
CGContextSetInterpolationQuality(bmContext, kCGInterpolationHigh);
CGColorSpaceRelease(colorSpace);
CGContextTranslateCTM(
bmContext,
+(rotatedRect.size.width/2),
+(rotatedRect.size.height/2));
CGContextRotateCTM(bmContext, angleInRadians);
CGContextTranslateCTM(
bmContext,
-(rotatedRect.size.width/2),
-(rotatedRect.size.height/2));
CGContextDrawImage(bmContext, CGRectMake(0, 0, rotatedRect.size.width, rotatedRect.size.height), imgRef);
CGImageRef rotatedImage = CGBitmapContextCreateImage(bmContext);
return rotatedImage;
As a result I getting distorted image. What I'm doing wrong here?
.
.
.
CGRect imgRect = CGRectMake(0., 0., width, height); // origin at {0, 0}; not {width, height}
.
.
.
CGImageRef rotatedImage = CGBitmapContextCreateImage(bmContext);
CGImageRelease(bmContext); // don't need this anymore
.
.
.
As commented, the origin is at 0.0, 0.0 not at width or height.
I am Rotating the image by using this code
- (CGImageRef)CGImageRotatedByAngle:(CGImageRef)imgRef angle:(CGFloat)angle
{
CGFloat angleInRadians = angle * (M_PI / 360);
CGFloat width = CGImageGetWidth(imgRef);
CGFloat height = CGImageGetHeight(imgRef);
CGRect imgRect = CGRectMake(0, 0, width, height);
CGAffineTransform transform = CGAffineTransformMakeRotation(angleInRadians);
CGRect rotatedRect = CGRectApplyAffineTransform(imgRect, transform);
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef bmContext = CGBitmapContextCreate(NULL,
rotatedRect.size.width,
rotatedRect.size.height,
8,
0,
colorSpace,
kCGImageAlphaPremultipliedFirst);
CGContextSetAllowsAntialiasing(bmContext, YES);
CGContextSetShouldAntialias(bmContext, YES);
CGContextSetInterpolationQuality(bmContext, kCGInterpolationHigh);
CGColorSpaceRelease(colorSpace);
CGContextTranslateCTM(bmContext,
+(rotatedRect.size.width/2),
+(rotatedRect.size.height/2));
CGContextRotateCTM(bmContext, angleInRadians);
CGContextTranslateCTM(bmContext,
-(rotatedRect.size.width/2),
-(rotatedRect.size.height/2));
CGContextDrawImage(bmContext, CGRectMake(0, 0,
rotatedRect.size.width,
rotatedRect.size.height),
imgRef);
CGImageRef rotatedImage = CGBitmapContextCreateImage(bmContext);
CFRelease(bmContext);
// [(id)rotatedImage autorelease];
return rotatedImage;
}
By this i am having the resultant image like this..
those white spaces should not be there and it should follow the same pattern of that size with out that white spaces around..the rotated image....
Please help..Thanks in advance
I'm using the OpenCV framework with XCode and want to convert from cvMat or IplImage to UIImage, how to do that? Thanks.
Note: most implementations don't correctly handle an alpha channel or convert from OpenCV's BGR pixel format to iOS's RGB.
This will correctly convert from cv::Mat to UIImage:
+(UIImage *)UIImageFromCVMat:(cv::Mat)cvMat {
NSData *data = [NSData dataWithBytes:cvMat.data length:image.step.p[0]*image.rows];
CGColorSpaceRef colorSpace;
CGBitmapInfo bitmapInfo;
if (cvMat.elemSize() == 1) {
colorSpace = CGColorSpaceCreateDeviceGray();
bitmapInfo = kCGImageAlphaNone | kCGBitmapByteOrderDefault;
} else {
colorSpace = CGColorSpaceCreateDeviceRGB();
bitmapInfo = kCGBitmapByteOrder32Little | (
cvMat.elemSize() == 3? kCGImageAlphaNone : kCGImageAlphaNoneSkipFirst
);
}
CGDataProviderRef provider = CGDataProviderCreateWithCFData((__bridge CFDataRef)data);
// Creating CGImage from cv::Mat
CGImageRef imageRef = CGImageCreate(
cvMat.cols, //width
cvMat.rows, //height
8, //bits per component
8 * cvMat.elemSize(), //bits per pixel
cvMat.step[0], //bytesPerRow
colorSpace, //colorspace
bitmapInfo, // bitmap info
provider, //CGDataProviderRef
NULL, //decode
false, //should interpolate
kCGRenderingIntentDefault //intent
);
// Getting UIImage from CGImage
UIImage *finalImage = [UIImage imageWithCGImage:imageRef];
CGImageRelease(imageRef);
CGDataProviderRelease(provider);
CGColorSpaceRelease(colorSpace);
return finalImage;
}
And to convert from UIImage to cv::Mat:
+ (cv::Mat)cvMatWithImage:(UIImage *)image
{
CGColorSpaceRef colorSpace = CGImageGetColorSpace(image.CGImage);
size_t numberOfComponents = CGColorSpaceGetNumberOfComponents(colorSpace);
CGFloat cols = image.size.width;
CGFloat rows = image.size.height;
cv::Mat cvMat(rows, cols, CV_8UC4); // 8 bits per component, 4 channels
CGBitmapInfo bitmapInfo = kCGImageAlphaNoneSkipLast | kCGBitmapByteOrderDefault;
// check whether the UIImage is greyscale already
if (numberOfComponents == 1){
cvMat = cv::Mat(rows, cols, CV_8UC1); // 8 bits per component, 1 channels
bitmapInfo = kCGImageAlphaNone | kCGBitmapByteOrderDefault;
}
CGContextRef contextRef = CGBitmapContextCreate(cvMat.data, // Pointer to backing data
cols, // Width of bitmap
rows, // Height of bitmap
8, // Bits per component
cvMat.step[0], // Bytes per row
colorSpace, // Colorspace
bitmapInfo); // Bitmap info flags
CGContextDrawImage(contextRef, CGRectMake(0, 0, cols, rows), image.CGImage);
CGContextRelease(contextRef);
return cvMat;
}
From opencv 2.4.6 on this functionality is already included.
Just include opencv2/highgui/ios.h
In OpenCV 3 this include has changed to:
opencv2/imgcodecs/ios.h
And you can use these functions:
UIImage* MatToUIImage(const cv::Mat& image);
void UIImageToMat(const UIImage* image, cv::Mat& m, bool alphaExist = false);
Here is the correct method to convert a cv::Mat to a UIImage.
Every other implementation I've seen — including OpenCV's documentation — is incorrect: they do not correctly convert from OpenCV's BGR to iOS's RGB, and they do not consider the alpha channel (if one exists). See comments above bitmapInfo = ….
+(UIImage *)UIImageFromCVMat:(cv::Mat)cvMat {
NSData *data = [NSData dataWithBytes:cvMat.data length:cvMat.elemSize()*cvMat.total()];
CGColorSpaceRef colorSpace;
CGBitmapInfo bitmapInfo;
if (cvMat.elemSize() == 1) {
colorSpace = CGColorSpaceCreateDeviceGray();
bitmapInfo = kCGImageAlphaNone | kCGBitmapByteOrderDefault;
} else {
colorSpace = CGColorSpaceCreateDeviceRGB();
// OpenCV defaults to either BGR or ABGR. In CoreGraphics land,
// this means using the "32Little" byte order, and potentially
// skipping the first pixel. These may need to be adjusted if the
// input matrix uses a different pixel format.
bitmapInfo = kCGBitmapByteOrder32Little | (
cvMat.elemSize() == 3? kCGImageAlphaNone : kCGImageAlphaNoneSkipFirst
);
}
CGDataProviderRef provider = CGDataProviderCreateWithCFData((__bridge CFDataRef)data);
// Creating CGImage from cv::Mat
CGImageRef imageRef = CGImageCreate(
cvMat.cols, //width
cvMat.rows, //height
8, //bits per component
8 * cvMat.elemSize(), //bits per pixel
cvMat.step[0], //bytesPerRow
colorSpace, //colorspace
bitmapInfo, // bitmap info
provider, //CGDataProviderRef
NULL, //decode
false, //should interpolate
kCGRenderingIntentDefault //intent
);
// Getting UIImage from CGImage
UIImage *finalImage = [UIImage imageWithCGImage:imageRef];
CGImageRelease(imageRef);
CGDataProviderRelease(provider);
CGColorSpaceRelease(colorSpace);
return finalImage;
}
You should consider using native OpenCV functions to convert forth and back :
#import <opencv2/imgcodecs/ios.h>
...
UIImage* MatToUIImage(const cv::Mat& image);
void UIImageToMat(const UIImage* image,
cv::Mat& m, bool alphaExist = false);
Here I am mentioning all the needed conversion methods together.
Converting UIImage color to UIImage gray, without using opencv and only using iOS library functions:
- (UIImage *)convertImageToGrayScale:(UIImage *)image
{
// Create image rectangle with current image width/height
CGRect imageRect = CGRectMake(0, 0, image.size.width, image.size.height);
// Grayscale color space
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceGray();
// Create bitmap content with current image size and grayscale colorspace
CGContextRef context = CGBitmapContextCreate(nil, image.size.width, image.size.height, 8, 0, colorSpace, kCGImageAlphaNone);
// Draw image into current context, with specified rectangle
// using previously defined context (with grayscale colorspace)
CGContextDrawImage(context, imageRect, [image CGImage]);
/* changes start here */
// Create bitmap image info from pixel data in current context
CGImageRef grayImage = CGBitmapContextCreateImage(context);
// release the colorspace and graphics context
CGColorSpaceRelease(colorSpace);
CGContextRelease(context);
// make a new alpha-only graphics context
context = CGBitmapContextCreate(nil, image.size.width, image.size.height, 8, 0, nil, kCGImageAlphaOnly);
// draw image into context with no colorspace
CGContextDrawImage(context, imageRect, [image CGImage]);
// create alpha bitmap mask from current context
CGImageRef mask = CGBitmapContextCreateImage(context);
// release graphics context
CGContextRelease(context);
// make UIImage from grayscale image with alpha mask
UIImage *grayScaleImage = [UIImage imageWithCGImage:CGImageCreateWithMask(grayImage, mask) scale:image.scale orientation:image.imageOrientation];
// release the CG images
CGImageRelease(grayImage);
CGImageRelease(mask);
// return the new grayscale image
return grayScaleImage;
}
Converting color UIImage to color cvMat. Please note that, you will find this piece of code in several links but there is a small modification here. Notice the portion "swap channels". This part is for keeping the color undisturbed otherwise the color channel got modified.
Also notice the following lines. These lines will help to keep the orientation of the image undisturbed.
if (image.imageOrientation == UIImageOrientationLeft
|| image.imageOrientation == UIImageOrientationRight) {
cols = image.size.height;
rows = image.size.width;
}
- (cv::Mat)cvMatFromUIImage:(UIImage *)image
{
CGColorSpaceRef colorSpace = CGImageGetColorSpace(image.CGImage);
CGFloat cols = image.size.width;
CGFloat rows = image.size.height;
if (image.imageOrientation == UIImageOrientationLeft
|| image.imageOrientation == UIImageOrientationRight) {
cols = image.size.height;
rows = image.size.width;
}
cv::Mat cvMat(rows, cols, CV_8UC4); // 8 bits per component, 4 channels (color channels + alpha)
CGContextRef contextRef = CGBitmapContextCreate(cvMat.data, // Pointer to data
cols, // Width of bitmap
rows, // Height of bitmap
8, // Bits per component
cvMat.step[0], // Bytes per row
colorSpace, // Colorspace
kCGImageAlphaNoneSkipLast |
kCGBitmapByteOrderDefault); // Bitmap info flags
CGContextDrawImage(contextRef, CGRectMake(0, 0, cols, rows), image.CGImage);
CGContextRelease(contextRef);
CGColorSpaceRelease(colorSpace);
//--swap channels -- //
std::vector<Mat> ch;
cv::split(cvMat,ch);
std::swap(ch[0],ch[2]);
cv::merge(ch,cvMat);
return cvMat;
}
Converting UIImage to cvMat gray. Notice the line
cv::Mat cvMat(rows, cols, CV_8UC4, Scalar(1,2,3,4)); // 8 bits per
component, 4 channels
instead of
cv::Mat cvMat(rows, cols, CV_8UC1); // 8 bits per component, 1
channels
This line is needed otherwise the code will throw error
- (cv::Mat)cvMatGrayFromUIImage:(UIImage *)image
{
CGColorSpaceRef colorSpace = CGImageGetColorSpace(image.CGImage);
CGFloat cols = image.size.width;
CGFloat rows = image.size.height;
// cv::Mat cvMat(rows, cols, CV_8UC1); // 8 bits per component, 1 channels
cv::Mat cvMat(rows, cols, CV_8UC4, Scalar(1,2,3,4)); // 8 bits per component, 4 channels
CGContextRef contextRef = CGBitmapContextCreate(cvMat.data, // Pointer to data
cols, // Width of bitmap
rows, // Height of bitmap
8, // Bits per component
cvMat.step[0], // Bytes per row
colorSpace, // Colorspace
kCGImageAlphaNoneSkipLast |
kCGBitmapByteOrderDefault); // Bitmap info flags
CGContextDrawImage(contextRef, CGRectMake(0, 0, cols, rows), image.CGImage);
CGContextRelease(contextRef);
CGColorSpaceRelease(colorSpace);
return cvMat;
}
Now finally, converting cvMat (color,binary, gray) to UIImage (color, binary, gray). Notice the line :
UIImage *finalImage = [UIImage imageWithCGImage:imageRef scale:1 orientation:self.originalImage.imageOrientation];
This line will help to keep the original orientation of the image
ENJOY !!
-(UIImage *)UIImageFromCVMat:(cv::Mat)cvMat {
NSData *data = [NSData dataWithBytes:cvMat.data length:cvMat.elemSize()*cvMat.total()];
CGColorSpaceRef colorSpace;
CGBitmapInfo bitmapInfo;
if (cvMat.elemSize() == 1) {
colorSpace = CGColorSpaceCreateDeviceGray();
bitmapInfo = kCGImageAlphaNone | kCGBitmapByteOrderDefault;
} else {
colorSpace = CGColorSpaceCreateDeviceRGB();
bitmapInfo = kCGBitmapByteOrder32Little | (
cvMat.elemSize() == 3? kCGImageAlphaNone : kCGImageAlphaNoneSkipFirst
);
}
CGDataProviderRef provider = CGDataProviderCreateWithCFData((__bridge CFDataRef)data);
// Creating CGImage from cv::Mat
CGImageRef imageRef = CGImageCreate(
cvMat.cols, //width
cvMat.rows, //height
8, //bits per component
8 * cvMat.elemSize(), //bits per pixel
cvMat.step[0], //bytesPerRow
colorSpace, //colorspace
bitmapInfo, // bitmap info
provider, //CGDataProviderRef
NULL, //decode
false, //should interpolate
kCGRenderingIntentDefault //intent
);
// Getting UIImage from CGImage
UIImage *finalImage = [UIImage imageWithCGImage:imageRef scale:1 orientation:self.originalImage.imageOrientation];
CGImageRelease(imageRef);
CGDataProviderRelease(provider);
CGColorSpaceRelease(colorSpace);
return finalImage;
}
You should consider using native OpenCV functions to convert forth and back :
#import <opencv2/imgcodecs/ios.h>
...
UIImage* MatToUIImage(const cv::Mat& image);
void UIImageToMat(const UIImage* image,
cv::Mat& m, bool alphaExist = false);
Note: if your UIImage comes from the camera, you should 'normalize' it (
iOS UIImagePickerController result image orientation after upload) before converting to cv::Mat since OpenCV does not take into account Exif data. If you don't do that the result should be misoriented.
As a category:
#import <UIKit/UIKit.h>
#import <opencv2/core/core.hpp>
using namespace cv;
#interface UIImage (OCV)
-(id)initWithOImage:(cv::Mat)oImage;
-(cv::Mat)oImage;
#end
and
#import "UIImage+OCV.h"
#implementation UIImage (OCV)
-(id)initWithOImage:(cv::Mat)oImage
{
NSData *data = [NSData dataWithBytes:oImage.data length:oImage.elemSize() * oImage.total()];
CGColorSpaceRef colorSpace;
if (oImage.elemSize() == 1) {
colorSpace = CGColorSpaceCreateDeviceGray();
} else {
colorSpace = CGColorSpaceCreateDeviceRGB();
}
CGDataProviderRef provider = CGDataProviderCreateWithCFData((__bridge CFDataRef)data);
CGImageRef imageRef = CGImageCreate(oImage.cols, // Width
oImage.rows, // Height
8, // Bits per component
8 * oImage.elemSize(), // Bits per pixel
oImage.step[0], // Bytes per row
colorSpace, // Colorspace
kCGImageAlphaNone | kCGBitmapByteOrderDefault, // Bitmap info flags
provider, // CGDataProviderRef
NULL, // Decode
false, // Should interpolate
kCGRenderingIntentDefault); // Intent
self = [self initWithCGImage:imageRef];
CGImageRelease(imageRef);
CGDataProviderRelease(provider);
CGColorSpaceRelease(colorSpace);
return self;
}
-(cv::Mat)oImage
{
CGColorSpaceRef colorSpace = CGImageGetColorSpace(self.CGImage);
CGFloat cols = self.size.width;
CGFloat rows = self.size.height;
cv::Mat cvMat(rows, cols, CV_8UC4); // 8 bits per component, 4 channels
CGContextRef contextRef = CGBitmapContextCreate(cvMat.data, // Pointer to backing data
cols, // Width of bitmap
rows, // Height of bitmap
8, // Bits per component
cvMat.step[0], // Bytes per row
colorSpace, // Colorspace
kCGImageAlphaNoneSkipLast |
kCGBitmapByteOrderDefault); // Bitmap info flags
CGContextDrawImage(contextRef, CGRectMake(0, 0, cols, rows), self.CGImage);
CGContextRelease(contextRef);
return cvMat;
}
#end
What I have experienced with converting between UIImage and cvMat is following:
When I used the method:
UIImage* MatToUIImage(const cv::Mat& image);
for converting cv::Mat to UIImage and the method:
void UIImageToMat(const UIImage* image, cv::Mat& m);
for converting UIImage to cv::Mat these methods didn't work correctly using the Simulator.
After I deployed my app on a real device, there weren't any problems.
Best regards,
Nazar
Help!
I've searched extensively and I haven't found a solution to this "simple" problem. What I am attempting to do is replace white pixels with alpha. It looks like CGImageCreateWithMaskingColors should give me what I want, unfortunately it returns nil in every case. Here's my code, what am I doing wrong?
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef context = CGBitmapContextCreate(NULL, size.width, size.height, 8, 4 * size.width, colorSpace, kCGImageAlphaPremultipliedFirst);
//draw a black background
CGContextSetRGBFillColor(context,0,0, 0, 1);
CGContextFillRect(context, CGRectMake(0, 0, size.width, size.height));
char* text2 = (char *)[text cStringUsingEncoding:NSASCIIStringEncoding];
CGContextSelectFont(context, "Helvetica Bold", kFontSize, kCGEncodingMacRoman);
CGContextSetTextDrawingMode(context, kCGTextFill);
//draw text with the "alpha" color white)
CGContextSetRGBFillColor(context, 1, 1, 1, 1);
float textLength = 20;
CGContextShowTextAtPoint(context, (size.width/2)-(textLength/2), ((size.height/2)-(kFontSize/2))+5, text2, strlen(text2));
//create the black/white image
CGImageRef alphaMask = CGBitmapContextCreateImage(context);
const float colorMasking[6] = {0xEE, 0xFF, 0xEE, 0xFF, 0xEE, 0xFF};
CGImageRef imageMasked = CGImageCreateWithMaskingColors(alphaMask, colorMasking);
imageMasked is nil no matter what I try. I would appreciate any help you can provide, thanks!
I'm having a UIView that renders some text using CoreText,everything works fine,
except for the fact that the entire view has black background color.
I've tried the most basic solutions like
[self setBackgroundColor:[UIColor clearColor]];
or
CGFloat components[] = {0.f, 0.f, 0.f, 0.f };
CGColorSpaceRef rgbColorSpace = CGColorSpaceCreateDeviceRGB();
CGColorRef transparent = CGColorCreate(rgbColorSpace, components);
CGContextSetFillColorWithColor(context, transparent);
CFRelease(transparent);
but this didn't help at all.
I'm just pounding my head on this issue, because I can't quite understand
how does really core text works and how is this pure-C layer related
with all the other objective-c stuff.
And this doesn't help very much in solving this problem,
so I'm asking you folks, if could you provide me a solution and (most important)
an explanation about it.
FIY I'm posting also the code of the CoreText view.
it's all based on 2 functions: parseText which builds up the CFAttributedString and the
drawRect that takes care of the drawing part.
-(void) parseText {
NSLog(#"rendering this text: %#", symbolHTML);
attrString = CFAttributedStringCreateMutable(kCFAllocatorDefault, 0);
CFAttributedStringReplaceString (attrString, CFRangeMake(0, 0), (CFStringRef)symbolHTML);
CFStringRef fontName = (CFStringRef)#"MetaSerif-Book-Accent";
CTFontRef myFont = CTFontCreateWithName((CFStringRef)fontName, 18.f, NULL);
CGColorSpaceRef rgbColorSpace = CGColorSpaceCreateDeviceRGB();
CGFloat components[] = { 1.0, 0.3f, 0.3f, 1.f };
CGColorRef redd = CGColorCreate(rgbColorSpace, components);
CFAttributedStringSetAttribute(attrString, CFRangeMake(0,0),
kCTForegroundColorAttributeName, redd);
CFRelease(redd);
CFAttributedStringSetAttribute(attrString, CFRangeMake(0, CFStringGetLength((CFStringRef)symbolHTML)), kCTFontAttributeName, myFont);
CTTextAlignment alignment = kCTLeftTextAlignment;
CTParagraphStyleSetting settings[] = {
{kCTParagraphStyleSpecifierAlignment, sizeof(alignment), &alignment}
};
CTParagraphStyleRef paragraphStyle = CTParagraphStyleCreate(settings, sizeof(settings) / sizeof(settings[0]));
CFAttributedStringSetAttribute(attrString, CFRangeMake(0, CFStringGetLength((CFStringRef)attrString)), kCTParagraphStyleAttributeName, paragraphStyle);
[self calculateHeight];
}
and this is the DrawRect function:
- (void)drawRect:(CGRect)rect {
/* get the context */
CGContextRef context = UIGraphicsGetCurrentContext();
/* flip the coordinate system */
float viewHeight = self.bounds.size.height;
CGContextTranslateCTM(context, 0, viewHeight);
CGContextScaleCTM(context, 1.0, -1.0);
CGContextSetTextMatrix(context, CGAffineTransformMakeScale(1.0, 1.0));
/* generate the path for the text */
CGMutablePathRef path = CGPathCreateMutable();
CGRect bounds = CGRectMake(0, 0, self.bounds.size.width-20.0, self.bounds.size.height);
CGPathAddRect(path, NULL, bounds);
/* draw the text */
CTFramesetterRef framesetter = CTFramesetterCreateWithAttributedString(attrString);
CTFrameRef frame = CTFramesetterCreateFrame(framesetter,
CFRangeMake(0, 0), path, NULL);
CFRelease(framesetter);
CFRelease(path);
CTFrameDraw(frame, context);
CGFloat components[] = {0.f, 0.f, 0.f, 0.f };
CGColorSpaceRef rgbColorSpace = CGColorSpaceCreateDeviceRGB();
CGColorRef transparent = CGColorCreate(rgbColorSpace, components);
CGContextSetFillColorWithColor(context, transparent);
CFRelease(transparent);
}
I hope that everything is clear, but if something looks
confusing, just ask and I'll be glad to explain myself better.
thank you in advance for this hardcore issue :)
k
Here's a question. Did you remember to set view.opaque = NO? Because if not you'll get that black background regardless of what else you do.