从 AdobeLabsUXMagicSelectionView (Adobe Creative SDK) 获取前景

Question

我正在尝试使用 AdobeLabsUXMagicSelectionView，但我遇到了 2 个问题。我想 "cut" selected 区域（前景）使用这两种方法：

方法 1) getForeground:andMatte: 它没有给我正确的前景。当我 select 一个区域并调用 getForeground:andMatte 我给我前景和背景（混合）。

选择狗的脸

割狗脸

文档说：

Alternatively, if you don’t need to process the underlying bitmap directly, and intend to use the results as inputs to CoreGraphics or CoreImage, you can call:

方法 2) 在此之后，我尝试 "cut" 就像文档中那样

extension AdobeLabsUXMagicSelectionView {

    func foregroundCGImage() -> CGImage {
        let w = size_t(self.image.size.width)
        let h = size_t(self.image.size.height)
        let data = UnsafeMutablePointer<UInt8>(malloc(4 * w * h * sizeof(UInt8)))
        self.readForegroundAndMatteIntoBuffer(data)

        for var i = 0; i < 4 * w * h; i += 4 {
            let alpha: UInt8 = UInt8(data[i + 3]) / 255
            data[i] *= alpha
            data[i + 1] *= alpha
            data[i + 2] *= alpha
        }

        let bitmapInfo = CGBitmapInfo(rawValue: CGImageAlphaInfo.NoneSkipLast.rawValue)
        let ctx = CGBitmapContextCreate(data, w, h, 8, 4 * w, CGColorSpaceCreateDeviceRGB(), bitmapInfo.rawValue)
        let imageRef = CGBitmapContextCreateImage(ctx)!

        return imageRef
    }

}

但它只绘制（黑色）图像的非 selected 部分（背景）。

有人可以帮忙吗？我想要的是获得 selected 区域的最终图像。

更新：

正如@DonWoodward 所说，我已经创建了这个类别：

@implementation AdobeLabsUXMagicSelectionView (Foreground)

- (UIImage *)getForeground {
    // show the results
    // first create a UIImage of just the foreground bits per the documentation in AdobeLabsUXMagicSelectionView.h
    size_t w = self.image.size.width;
    size_t h = self.image.size.height;

    uint8_t *data = (uint8_t *)malloc(4*w*h*sizeof(uint8_t));
    [self readForegroundAndMatteIntoBuffer:data];

    // Paint the non-selected portion of the image black
    for (int i = 0; i < 4*w*h; i += 4) {
        float alpha = (float)data[i + 3] / 255;
        data[i    ] *= alpha;
        data[i + 1] *= alpha;
        data[i + 2] *= alpha;
    }
    CGContextRef ctx = CGBitmapContextCreate(data, w, h, 8, 4*w, CGColorSpaceCreateDeviceRGB(), (CGBitmapInfo)kCGImageAlphaNoneSkipLast);
    CGImageRef imageRef = CGBitmapContextCreateImage(ctx);
    UIImage * foregroundBits = [UIImage imageWithCGImage:imageRef];
    CGImageRelease(imageRef);

    return foregroundBits;
}

@end

但是结果"foreground"周围有很多黑色像素。

我需要什么？获取 "clean" 前景（selected 区域，没有黑色像素）以覆盖 UIImageView

Answer 1

我认为问题在于您的比例因子是 uint8_t 类型，因此您将比例因子裁剪为零。使它成为一个浮动，它应该可以工作。这是来自 MagicPuppy（在 objective c 中）的代码：

    // show the results
    // first create a UIImage of just the foreground bits per the documentation in AdobeLabsUXMagicSelectionView.h
    size_t w = _magicSelectionView.image.size.width;
    size_t h = _magicSelectionView.image.size.height;

    uint8_t *data = (uint8_t *)malloc(4*w*h*sizeof(uint8_t));
    [_magicSelectionView readForegroundAndMatteIntoBuffer:data];

    // Paint the non-selected portion of the image black
    for (int i = 0; i < 4*w*h; i += 4)
    {
        float alpha = (float)data[i + 3] / 255;
        data[i    ] *= alpha;
        data[i + 1] *= alpha;
        data[i + 2] *= alpha;
    }
    CGContextRef ctx = CGBitmapContextCreate(data, w, h, 8, 4*w, CGColorSpaceCreateDeviceRGB(), (CGBitmapInfo)kCGImageAlphaNoneSkipLast);
    CGImageRef imageRef = CGBitmapContextCreateImage(ctx);
    UIImage * foregroundBits = [UIImage imageWithCGImage:imageRef];
    CGImageRelease(imageRef);

    // show the results
    _resultsView = [[UIImageView alloc] initWithFrame: CGRectMake(0, VIEW_Y_OFFSET, self.view.bounds.size.width, self.view.bounds.size.height-VIEW_Y_OFFSET)];
    _resultsView.contentMode = UIViewContentModeScaleAspectFit;
    [_resultsView setImage: foregroundBits];
    [self.view addSubview: _resultsView];

Answer 2

在这种情况下，您将 RGB 通道预乘以您的 alpha 通道，这意味着您希望在创建上下文时使用 kCGImageAlphaPremultipliedLast，如：

// Paint the non-selected portion of the image black
for (int i = 0; i < 4*w*h; i += 4)
{
    float alpha = (float)data[i + 3] / 255;
    data[i    ] *= alpha;
    data[i + 1] *= alpha;
    data[i + 2] *= alpha;
}
CGContextRef ctx = CGBitmapContextCreate(data, w, h, 8, 4*w, CGColorSpaceCreateDeviceRGB(), (CGBitmapInfo)kCGImageAlphaPremultipliedLast);
CGImageRef imageRef = CGBitmapContextCreateImage(ctx);
UIImage * foregroundBits = [UIImage imageWithCGImage:imageRef];
CGImageRelease(imageRef);

可以在 CGImage docs

中找到更多信息

此外，您还可以尝试将 CGImageCreateWithMask 与

的输出一起使用

- (void)getForeground:(UIImage **)foregroundImage andMatte:(UIImage **)matteImage

如Quartz 2D Programming Guide

中所述

UIImage *fg;
UIImage *matte;

[_magicSelectionView getForeground:&fg andMatte:&matte];

CGImageRef mattedForeground = CGImageCreateWithMask(fg.CGImage, matte.CGImage);
UIImage *foregroundBits = [UIImage imageWithCGImage:mattedForeground];

// show the results
_resultsView = [[UIImageView alloc] initWithFrame: CGRectMake(0, VIEW_Y_OFFSET, self.view.bounds.size.width, self.view.bounds.size.height-VIEW_Y_OFFSET)];
_resultsView.contentMode = UIViewContentModeScaleAspectFit;
[_resultsView setImage: foregroundBits];
[self.view addSubview: _resultsView];

如果这些都不起作用，则用于呈现结果的 UIImageViews 的配置可能存在一些问题，但如果没有该代码，则很难说。

从 AdobeLabsUXMagicSelectionView (Adobe Creative SDK) 获取前景

Get foreground from AdobeLabsUXMagicSelectionView (Adobe Creative SDK)

core-graphics

uiimage

cgimage

ios

adobecreativesdk

从 Adob​​eLabsUXMagicSelectionView (Adobe Creative SDK) 获取前景

Get foreground from AdobeLabsUXMagicSelectionView (Adobe Creative SDK)

core-graphics

uiimage

cgimage

ios

adobecreativesdk

从 AdobeLabsUXMagicSelectionView (Adobe Creative SDK) 获取前景