Lesson 3 - Official Topic

what is the different between mult=2 or 1 or 3 etc?

1 Like

Sorry for posting in the wrong forum, @sgugger!

The book states …

"On each epoch (which is one complete pass through all of our images in the dataset) we randomly select a different part of each image. "

But I thought the transformations were applied per batch … not per epoch.

1 Like

Think any of these transforms be better than padding (adding empty useless pixels).

That is incorrect, batch_tfms can apply a different transformation to each image. Rotation for instance, or flip, are random per image.

1 Like

A post was merged into an existing topic: Lesson 3 - Non-beginner discussion

On the validation set, we center crop the image if it’s ratio isn’t in the range (to the minmum or maximum value) then resize. Link is:
Documentation of RandomResizedCrop

2 Likes

At each epoch you get a new transformation.

Are there pre-packaged transformations that are not affine? Things like lightness, hue, sharpness…

what’s the best rule of thumb with regards to how large a batch to feed at a time relative to gpu size?

A post was merged into an existing topic: Lesson 3 - Non-beginner discussion

Is there any significance to the size of the crop to be 224x224 ?

There is lightning and contrast transforms, randomly erasing a part of the image, perspective warping. Look at the docs on vision.augment for the whole list.

2 Likes

Either inherit new class from Transform or create new function with @Transform decorator.

Jeremy runs through these in source code walkthru videos.

If the data set in imbalanced, can I choose to augment only the under represented class? or choose a particular type of transformation that suits a class best.

Usually, whatever fits on your GPU is fine.

So the transformation is the same to each image per epoch? Just wanna make sure I understand.

1 Like

How do you pick what augmentations to do? Do certain augmentations work better than others for a task? Does it make sense to schedule augmentations during training?

training will be faster and you can iterate on your model

Why 224 not say 480 , 720 which is close to capture sizes ?