将pytorch模型转为coreml后，预测结果差很多答案

【问题标题】：After converting the pytorch model to coreml, the prediction results are much worse将pytorch模型转为coreml后，预测结果差很多
【发布时间】：2021-04-02 23:05:00
【问题描述】：

将pytorch模型转成coreml后，预测结果差很多。你怎么看，可能是什么问题？在转换过程中，我收到警告：警告：根：在图形输出中检测到元组。这将在转换后的模型中展平。和警告：root：函数 main 中 i32 类型的输出 var reduce_argmax_1 被强制转换为 fp32 类型。

我的模特：

class Net(nn.Module):
        def __init__(self,NumClasses,PreTrainedModelPath="", UpdateEncoderBatchNormStatistics=True): 
            super(Net, self).__init__()
            self.Encoder = densenet_cosine_264_k32.densenet_cosine_264_k32
            if not PreTrainedModelPath=="":
                self.Encoder.load_state_dict(torch.load(PreTrainedModelPath))
                print ("Dense net encoder weights loaded")
            if not UpdateEncoderBatchNormStatistics:
                self.Encoder.eval()
            self.SkipConnectionLayers=[2,12,28,96]#,147]
            self.PSPScales = [1, 1 / 2, 1 / 4, 1 / 8] 
            self.PSPLayers = nn.ModuleList()
            for Ps in self.PSPScales:
                self.PSPLayers.append(nn.Sequential(
                    nn.Conv2d(2688, 1024, stride=1, kernel_size=3, padding=1, bias=True)))
            self.PSPSqueeze = nn.Sequential(
                nn.Conv2d(4096, 512, stride=1, kernel_size=1, padding=0, bias=False),
                nn.BatchNorm2d(512),
                nn.ReLU()
            )
            self.SkipConnections = nn.ModuleList()
            self.SkipConnections.append(nn.Sequential(
                nn.Conv2d(1152, 512, stride=1, kernel_size=1, padding=0, bias=False),
                nn.BatchNorm2d(512),
                nn.ReLU()))
            self.SkipConnections.append(nn.Sequential(
                nn.Conv2d(256, 256, stride=1, kernel_size=1, padding=0, bias=False),
                nn.BatchNorm2d(256),
                nn.ReLU()))
            self.SqueezeUpsample = nn.ModuleList()
            self.SqueezeUpsample.append(nn.Sequential(
                nn.Conv2d(1024, 512, stride=1, kernel_size=1, padding=0, bias=False),
                nn.BatchNorm2d(512),
                nn.ReLU()
            ))
            self.SqueezeUpsample.append(nn.Sequential(
                nn.Conv2d(256+512, 256, stride=1, kernel_size=1, padding=0, bias=False),
                nn.BatchNorm2d(256),
                nn.ReLU()
            ))
            self.FinalPrdiction=nn.Conv2d(256, NumClasses, stride=1, kernel_size=3, padding=1, bias=False)
            self=self.cuda()

        def forward(self,Images, EvalMode=False):
                RGBMean = [123.68,116.779,103.939]
                RGBStd = [65,65,65]
                #InpImages = torch.autograd.Variable(torch.from_numpy(Images.astype(float)), requires_grad=False).transpose(2,3).transpose(1, 2).type(torch.FloatTensor)
                #InpImages = torch.autograd.Variable(torch.from_numpy(Images.astype(float)),requires_grad=False).transpose(2, 3).transpose(1, 2).type(torch.HalfTensor)
        
                InpImages = torch.autograd.Variable(Images)
                InpImages=InpImages.cuda()
                for i in range(len(RGBMean)): InpImages[:, i, :, :]=(InpImages[:, i, :, :]-RGBMean[i])/RGBStd[i] 
                x=InpImages
                SkipConFeatures=[] 
                for i in range(147):
                    x=self.Encoder[i](x)
                    if i in self.SkipConnectionLayers:
                         SkipConFeatures.append(x)
                PSPSize=(x.shape[2],x.shape[3])
                PSPFeatures=[] 
                for i,Layer in enumerate(self.PSPLayers): 
                      NewSize=np.ceil(np.array(PSPSize)*self.PSPScales[i]).astype(np.int)
                      y = nn.functional.interpolate(x, tuple(NewSize), mode='bilinear')
                      y = Layer(y)
                      y = nn.functional.interpolate(y, PSPSize, mode='bilinear')
                      PSPFeatures.append(y)
                x=torch.cat(PSPFeatures,dim=1)
                x=self.PSPSqueeze(x)
                for i in range(len(self.SkipConnections)):
                  sp=(SkipConFeatures[-1-i].shape[2],SkipConFeatures[-1-i].shape[3])
                  x=nn.functional.interpolate(x,size=sp,mode='bilinear')
                  x = torch.cat((self.SkipConnections[i](SkipConFeatures[-1-i]),x), dim=1)
                  x = self.SqueezeUpsample[i](x)
                x = self.FinalPrdiction(x) 
                x = nn.functional.interpolate(x,size=InpImages.shape[2:4],mode='bilinear')
                Prob=F.softmax(x,dim=1) 
                tt,Labels=x.max(1) 
                return Prob, Labels


Net = Net(NumClasses=3) 
Net.load_state_dict(torch.load(Trained_model_path)) 
Net.eval()

import coremltools
mlmodel = coremltools.converters.convert(
  traced_model,
  inputs=[coremltools.TensorType(shape=(1, 3, 255, 255))],
)

我期待任何建议

【问题讨论】：

标签： pytorch coreml coremltools

【解决方案1】：

您在转换模型时还需要指定以下内容：

                RGBMean = [123.68,116.779,103.939]
                RGBStd = [65,65,65]

您这样做会使输入成为图像，而不是张量。有关实际语法，请参阅 coremltools 文档。

【讨论】：