Hi Rayan,
The error message you are seeing might be because the output of transform is not returning the data in the expected format for your neural network.
The “transform” function outputs a “TransformedDatastore” object. With the Deep Network Designer, you can import and train any datastore object that works with the trainNetwork function.
To pre-process images according to your own pipeline, try using the transform and combine functions.
For more information on pre-processing images for deep learning applications, see Preprocess Images for Deep Learning.
As a last resort solution for this issue, you could consider using the “Image Batch Processor” app from the Image Processing Toolbox to perform any pre-processing operations on your image dataset and save them to your local disk.
However, I would only recommend this option if your dataset were small, and you would not mind having a second copy of the images on your disk.
