iphone image resolution increased when emailed - iphone

Question

In my app i capture an image and then add a frame to it...
I also have the feature to add custom text on the final image (original image + frame). I am using the following code to draw the text.
-(UIImage *)addText:(UIImage *)img text:(NSString *)textInput
{
CGFloat imageWidth = img.size.width;
CGFloat imageHeigth = img.size.height;
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef context = CGBitmapContextCreate(NULL, imageWidth, imageHeigth, 8,
4 * imageWidth, colorSpace, kCGImageAlphaPremultipliedFirst);
CGContextDrawImage(context, CGRectMake(0, 0, imageWidth, imageHeigth), img.CGImage);
CGContextSetCMYKFillColor(context, 0.0, 0.0, 0.0, 1.0,1);
CGContextSetFont(context, customFont);
UIColor * strokeColor = [UIColor blackColor];
CGContextSetFillColorWithColor(context, strokeColor.CGColor);
CGContextSetFontSize(context, DISPLAY_FONT_SIZE * DisplayToOutputScale);
// Create an array of Glyph's the size of text that will be drawn.
CGGlyph textToPrint[[textInput length]];
for (int i = 0; i < [textInput length]; ++i)
{
// Store each letter in a Glyph and subtract the MagicNumber to get appropriate value.
textToPrint[i] = [textInput characterAtIndex:i] + 3 - 32;
}
// First pass to be displayed invisible, will be used to calculate the length of the text in glyph
CGContextSetTextDrawingMode(context, kCGTextInvisible);
CGContextShowGlyphsAtPoint(context, 0 , 0 , textToPrint, [textInput length]);
CGPoint endPoint = CGContextGetTextPosition(context);
// Calculate position of text on white border frame
CGFloat xPos = (imageWidth/2.0f) - (endPoint.x/2.0f);
CGFloat yPos;
yPos = 30 * DisplayToOutputScale;
// Toggle off invisible mode, we are ready to draw the text
CGContextSetTextDrawingMode(context, kCGTextFill);
CGContextShowGlyphsAtPoint(context, xPos , yPos , textToPrint, [textInput length]);
// Extract resulting image
CGImageRef imageMasked = CGBitmapContextCreateImage(context);
CGContextRelease(context);
CGColorSpaceRelease(colorSpace);
return [UIImage imageWithCGImage:imageMasked];
}
I email the image using UIImageJPEGRepresentation and attach the data.
When i email the image without adding custom text the image size increases from 1050 x 1275 to 2100 x 2550 which is strange.
But when i email the image with text added the image size remains unchanged.
Can any one explain me why this happens ??
I think there is something to do with converting from UIImage to UIData.
Thanx

Answer 1

I had the same problem. Fix it with starting the context with a scale of 1:
UIGraphicsBeginImageContextWithOptions(size, YES, 1.0);