# Data augmentation transforms
This page lists data augmentation transforms used in DAN.
## Individual augmentation transforms
### Elastic Transform
| | Elastic Transform |
| ---------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| Description | This transformation applies local distortions that rotate characters locally. |
| Comments | The impact of this transformation is mostly visible on documents, not so much on lines. Results are comparable to the original DAN implementation. |
| Documentation | See the [`albumentations` documentation](https://albumentations.ai/docs/api_reference/augmentations/geometric/transforms/#albumentations.augmentations.geometric.transforms.ElasticTransform) |
| Examples |   |
| CPU time (seconds/10 images) | 0.44 (3013x128 pixels) / 0.86 (1116x581 pixels) |
### PieceWise Affine
!!! warning
This transform is temporarily removed from the pipeline until [this issue](https://github.com/albumentations-team/albumentations/issues/1442) is fixed.
| | PieceWise Affine |
| ---------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| Description | This transformation also applies local distortions but with a larger grid than ElasticTransform. |
| Comments | This transformation is very slow. It is a new transform that was not in the original DAN implementation. |
| Documentation | See the [`albumentations` documentation](https://albumentations.ai/docs/api_reference/augmentations/geometric/transforms/#albumentations.augmentations.geometric.transforms.PiecewiseAffine) |
| Examples |   |
| CPU time (seconds/10 images) | 2.92 (3013x128 pixels) / 3.76 (1116x581 pixels) |
### Dilation Erosion
| | Dilation & Erosion |
| ---------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| Description | This transformation makes the pen stroke thicker or thinner. |
| Comments | The `RandomDilationErosion` class randomly selects a kernel size and applies a dilation or an erosion to the image. It relies on opencv and is similar to the original DAN implementation. |
| Documentation | See the [`opencv` documentation](https://docs.opencv.org/3.4/db/df6/tutorial_erosion_dilatation.html) |
| Examples |   |
| CPU time (seconds/10 images) | 0.02 (3013x128 pixels) / 0.03 (1116x581 pixels) |
### Sharpen
| | Sharpen |
| ---------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| Description | This transformation makes the image sharper. |
| Comments | Similar to the original DAN implementation. |
| Documentation | See the [`albumentations` documentation](https://albumentations.ai/docs/api_reference/augmentations/transforms/#albumentations.augmentations.transforms.Sharpen) |
| Examples |   |
| CPU time (seconds/10 images) | 0.02 (3013x128 pixels) / 0.04 (1116x581 pixels) |
### Color Jittering
| | Color Jittering |
| ---------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| Description | This transformation alters the colors of the image. |
| Comments | Similar to the original DAN implementation. |
| Documentation | See the [`albumentations` documentation](https://albumentations.ai/docs/api_reference/augmentations/transforms/#albumentations.augmentations.transforms.ColorJitter) |
| Examples |   |
| CPU time (seconds/10 images) | 0.03 (3013x128 pixels) / 0.04 (1116x581 pixels) |
### Gaussian Noise
| | Gaussian Noise |
| ---------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| Description | This transformation adds Gaussian noise to the image. |
| Comments | The noise from the original DAN implementation is more uniform. |
| Documentation | See the [`albumentations` documentation](https://albumentations.ai/docs/api_reference/augmentations/transforms/#albumentations.augmentations.transforms.GaussianNoise) |
| Examples |   |
| CPU time (seconds/10 images) | 0.29 (3013x128 pixels) / 0.53 (1116x581 pixels) |
### Gaussian Blur
| | Gaussian Blur |
| ---------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| Description | This transformation blurs the image. |
| Comments | Similar to the original DAN implementation. |
| Documentation | See the [`albumentations` documentation](https://albumentations.ai/docs/api_reference/augmentations/transforms/#albumentations.augmentations.transforms.GaussianBlur) |
| Examples |   |
| CPU time (seconds/10 images) | 0.01 (3013x128 pixels) / 0.02 (1116x581 pixels) |
### Random Perspective
| | Random Perspective |
| ---------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| Description | This transformation changes the perspective from which the photo is taken. |
| Comments | Similar to the original DAN implementation. |
| Documentation | See the [`albumentations` documentation](https://albumentations.ai/docs/api_reference/augmentations/transforms/#albumentations.augmentations.transforms.Perspective) |
| Examples |   |
| CPU time (seconds/10 images) | 0.05 (3013x128 pixels) / 0.05 (1116x581 pixels) |
### Shearing (x-axis)
| | Shearing (x-axis) |
| ---------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| Description | This transformation changes the slant of the text on the image. |
| Comments | New transform that was not in the original DAN implementation. |
| Documentation | See the [`albumentations` documentation](https://albumentations.ai/docs/api_reference/augmentations/geometric/transforms/#albumentations.augmentations.geometric.transforms.Affine) |
| Examples |   |
| CPU time (seconds/10 images) | 0.05 (3013x128 pixels) / 0.04 (1116x581 pixels) |
### Coarse Dropout
| | Coarse Dropout |
| ---------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| Description | This transformation adds dropout on the image, turning small patches into black pixels. |
| Comments | It is a new transform that was not in the original DAN implementation. |
| Documentation | See the [`albumentations` documentation](https://albumentations.ai/docs/api_reference/augmentations/dropout/coarse_dropout/#coarsedropout-augmentation-augmentationsdropoutcoarse_dropout) |
| Examples |   |
| CPU time (seconds/10 images) | 0.02 (3013x128 pixels) / 0.02 (1116x581 pixels) |
### Random Scale
| | RandomScale |
| ------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| Description | This transformation downscales the image from a random factor. |
| Comments | The original DAN implementation reimplemented it as [DPIAdjusting](https://github.com/FactoDeepLearning/DAN/blob/da3046a1cc83e9be3e54dd31a5e74d6134d1ebdc/basic/transforms.py#L62). |
| Documentation | See the [`albumentations` documentation](https://albumentations.ai/docs/api_reference/augmentations/geometric/resize/#albumentations.augmentations.geometric.resize.RandomScale) |
| Examples |   |
### To Gray
| | ToGray |
| ---------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| Description | This transformation transforms an RGB image into grayscale. |
| Comments | It is a new transform that was not in the original DAN implementation. |
| Documentation | See the [`albumentations` documentation](https://albumentations.ai/docs/api_reference/augmentations/transforms/#albumentations.augmentations.transforms.ToGray) |
| Examples |   |
| CPU time (seconds/10 images) | 0.02 (3013x128 pixels) / 0.02 (1116x581 pixels) |
## Full augmentation pipeline
- Data augmentation is applied with a probability of 0.9.
- In this case, two transformations are randomly selected to be applied.
- Reproducibility is possible by setting `random.seed` and `np.random.seed` (already done in `dan/ocr/document/train.py`)
- Examples with new pipeline:
