iphone image resolution increased when emailed

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开发者_如何学编程(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

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I had the same problem. Fix it with starting the context with a scale of 1:

UIGraphicsBeginImageContextWithOptions(size, YES, 1.0);