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lovelyelfpop avatar lovelyelfpop commented on August 30, 2024

应该是反复压缩内存没释放

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kukumaluCN avatar kukumaluCN commented on August 30, 2024

只是处理了一张高清的大图。

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GuoZhiQiang avatar GuoZhiQiang commented on August 30, 2024

@kukumaluCN 把图片发给我，我调试一下，看这个 250M 是怎么增加的

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kukumaluCN avatar kukumaluCN commented on August 30, 2024

这张图在我们的内网测试环境，外网链接我没法提供，原图太大，图床不支持上传，可以邮件私发你。

这个是我写的测试demo，原图加载时，转data估算的大小：

这个是用您的方法压缩后测算的大小，以及对应的内存峰值。可以看到，原始图片读入内存瞬时峰值在230M左右，压缩峰值瞬时能到248M！我的测试机是7P。

我参考了微信的压缩机制，改用了自己的一套压缩算法，效果如下，相对优化了很多，但是还是有压缩瞬间的内存峰值：

测试的核心代码如下：

//鲁班压缩：
if (self.flag) {
    self.flag = NO;
    UIImage *image = [UIImage imageNamed:@"ada9dcab6fe0452488539bd31782a272.JPG"];
    //鲁班压缩
    NSData *data = [UIImage lubanCompressImage:image];
    UIImage *finalCompressImage = [UIImage imageWithData:data];
    self.imageView.image = finalCompressImage;
    
    CGFloat le = data.length/1024.0/1024.0;
    self.label.text = [NSString stringWithFormat:@"压缩后:%.0fx%.0f - %fMB", self.imageView.image.size.width, self.imageView.image.size.height, le];
}
else {
    self.flag = YES;
    self.imageView.image = [UIImage imageNamed:@"ada9dcab6fe0452488539bd31782a272.JPG"];
    
    NSData *data = UIImageJPEGRepresentation(self.imageView.image, 1.0);
    CGFloat le = data.length/1024.0/1024.0;
    self.label.text = [NSString stringWithFormat:@"原图:%.0fx%.0f - %fMB", self.imageView.image.size.width, self.imageView.image.size.height, le];
}
//微信压缩：
if (self.flag) {
    self.flag = NO;
    UIImage *image = [UIImage imageNamed:@"ada9dcab6fe0452488539bd31782a272.JPG"];
    //裁剪压缩，以1280为边界值动态裁剪
    UIImage *compressImage = [image wx_compressLargeImage];
    //二次压缩图像，防止裁剪后依旧为高清图
    NSData *data = UIImageJPEGRepresentation(compressImage, 0.5);
    UIImage *finalCompressImage = [UIImage imageWithData:data];
    self.imageView.image = finalCompressImage;
    
    CGFloat le = data.length/1024.0/1024.0;
    self.label.text = [NSString stringWithFormat:@"压缩后:%.0fx%.0f - %fMB", self.imageView.image.size.width, self.imageView.image.size.height, le];
}
else {
    self.flag = YES;
    self.imageView.image = [UIImage imageNamed:@"ada9dcab6fe0452488539bd31782a272.JPG"];
    
    NSData *data = UIImageJPEGRepresentation(self.imageView.image, 1.0);
    CGFloat le = data.length/1024.0/1024.0;
    self.label.text = [NSString stringWithFormat:@"原图:%.0fx%.0f - %fMB", self.imageView.image.size.width, self.imageView.image.size.height, le];
}

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kukumaluCN avatar kukumaluCN commented on August 30, 2024

其实最消耗内存的是UIImageJPEGRepresentation(self.imageView.image, 1.0);这个方法，取消之后，加载原始图片，基本没有那么高的瞬时内存尖峰。

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GuoZhiQiang avatar GuoZhiQiang commented on August 30, 2024

@kukumaluCN [email protected] 另外我看了下，你测试的代码是为了较少峰值而牺牲了压缩质量，我个人认为这样压缩出来的大小并不是最理想的。

你测试的工程如果方便的话也发给我一下下。另外压缩这么大的图片，我还是第一次，也算是个机会看压缩超大图能不能造出来另外一种机制。

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kukumaluCN avatar kukumaluCN commented on August 30, 2024

关注内存峰值是必须的，因为我们项目的特殊性，需要兼容比较老的设备，运存512M那种，我们测试发现，瞬时内存峰值超过200M，就会造成crash，所以没办法，必须优化内存占用和内存峰值。
关于压缩质量，其实我做过对比，上面的那些图看不清楚，其实微信的压缩算法很优秀，压缩过后的大小能控制在400k左右，但是清晰度高很多，您压缩后的图片大小会小很多，但是清晰度不太够。
下面是对比，图片放大了5X的局部展示：

这个是微信的压缩算法，微信以1280为边界值做裁剪压缩处理，压缩系数0.5：

这个是微信的压缩算法，微信以1280为边界值做裁剪压缩处理，压缩系数0.1：

这个是您提供的压缩机制：

微信的压缩算法我参考了这个：iOS 图片压缩----微信图片处理策略，并做了算法优化，原理是一致的，关于压缩系数，取了0.5，这个产出和文中说的一致，和微信朋友圈的相当。
不过，这套算法依旧使用了UIImageJPEGRepresentation这个函数，这个是导致内存峰值的罪魁祸首，目前还没找到更好的方法，有人说微信还使用了ImageIO，算法如下，但是经过测算，内存占用不降反升。。。我也很想找到一个压缩大图的比较好的方案，很希望和您探讨。

+ (UIImage *)jxt_scaledImageWithData:(NSData *)data toSize:(CGSize)size
{
    if (!data) {
        return nil;
    }
    UIImage *thumbnail = nil;
    CGImageSourceRef sourceRef = CGImageSourceCreateWithData((__bridge CFDataRef)data, nil);
    if (sourceRef) {
        CGFloat maxPixelSize = MAX(size.width, size.height);
        NSDictionary *options = @{
                                  (__bridge id)kCGImageSourceCreateThumbnailFromImageAlways:(__bridge id)kCFBooleanTrue,
                                  (__bridge id)kCGImageSourceCreateThumbnailWithTransform:(__bridge id)kCFBooleanTrue,
                                  (__bridge id)kCGImageSourceThumbnailMaxPixelSize:[NSNumber numberWithFloat:maxPixelSize]
                                  };
        CGImageRef imageRef = CGImageSourceCreateThumbnailAtIndex(sourceRef, 0, (__bridge CFDictionaryRef)options);
        if (imageRef) {
            thumbnail = [UIImage imageWithCGImage:imageRef];
            CGImageRelease(imageRef);
        }
        CFRelease(sourceRef);
    }
    return thumbnail;
}

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kukumaluCN avatar kukumaluCN commented on August 30, 2024

我还发现，下面两个方式获取到的data的length，同一张图片，是有较大偏差的，有人说，第一个方法，系数要取0.7才可以。。。

NSData *data = UIImageJPEGRepresentation(self.imageView.image, 1.0);
NSData *data = [NSData dataWithContentsOfFile:retinaPath];

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kukumaluCN avatar kukumaluCN commented on August 30, 2024

图片已经发送至您的邮箱，期待进一步交流。

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GuoZhiQiang avatar GuoZhiQiang commented on August 30, 2024

@kukumaluCN 好的好的👌。微信压缩的那个我之前看过也实现过，但 压缩后的大小我还是接受不了，清晰是很清晰，不适合多图上传的场景。于是实现了luban。在实际场景中，10张图片，用微信那个压缩后5M左右，luban压缩完1M左右，清晰度也还可以，当然了如果要更清晰的可以下载原图。

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GuoZhiQiang avatar GuoZhiQiang commented on August 30, 2024

另外给你们产品经理商量一下，为什么有这么大的图片？

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GuoZhiQiang avatar GuoZhiQiang commented on August 30, 2024

对于一般场景为了避免使用 UIImageJPEGRepresentation 造成的内存暴涨 可以使用下面的方法进行压缩处理:

//imageURL 图片的本地存储地址; size 图片大小; scale 压缩比 0.0~1.0
- (UIImage* _Nullable)downsampleImageURL:(NSURL *)imageURL sampleSize:(CGSize)size scale:(CGFloat)scale
{
    CFDictionaryRef sourceOpt = (__bridge CFDictionaryRef)@{(NSString *)kCGImageSourceShouldCache: @NO};
    CGImageSourceRef source = CGImageSourceCreateWithURL((CFURLRef)imageURL, sourceOpt);
    if (!source) {
        NSLog(@"imageSource is Null!");
        return nil;
    }
    int maxDimension = MAX(size.width, size.height) * scale;
    CFDictionaryRef downsampleOpt = (__bridge CFDictionaryRef)@{
        (NSString *)kCGImageSourceCreateThumbnailFromImageAlways : @YES,
        (NSString *)kCGImageSourceShouldCacheImmediately : @YES ,
        (NSString *)kCGImageSourceCreateThumbnailWithTransform : @YES,
        (NSString *)kCGImageSourceThumbnailMaxPixelSize : @(maxDimension)};
    CGImageRef downsampleImage = CGImageSourceCreateThumbnailAtIndex(source, 0, downsampleOpt);
    CFRelease(source);
    
    return [UIImage imageWithCGImage:downsampleImage];
}

在本例中使用 可以这样子：

    NSString *filePaht = [[NSBundle mainBundle] pathForResource:@"IMG_1998" ofType:@"JPG"];
    UIImage *imgData   = [UIImage imageWithContentsOfFile:filePaht];
    NSURL *urlPath = [NSURL fileURLWithPath:filePaht];
    self.imgCompressed    = [self downsampleImageURL:urlPath sampleSize:imgData.size scale:0.3];
    self.img_brower.image = _imgCompressed;

@kukumaluCN @lovelyelfpop

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zhaozzq avatar zhaozzq commented on August 30, 2024 
   //裁剪压缩，以1280为边界值动态裁剪
   UIImage *compressImage = [image wx_compressLargeImage];

@kukumaluCN 您好，这里的微信压缩有开源的实现或者能提供一下代码吗？我想测试一下效果

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