Added crop augmentation (#41)

* Added crop augmentations

* bugfix

albumentations/augmentations/functional.py

@@ -79,6 +79,36 @@ def shift_scale_rotate(img, angle, scale, dx, dy, interpolation=cv2.INTER_LINEAR
     return img
 
 
+def crop(img, x_min, y_min, x_max, y_max):
+    height, width = img.shape[:2]
+    if x_max <= x_min or y_max <= y_min:
+        raise ValueError(
+            'We should have x_min < x_max and y_min < y_max. But we got'
+            ' (x_min = {x_min}, y_min = {y_min}, x_max = {x_max}, y_max = {y_max})'.format(
+                x_min=x_min,
+                x_max=x_max,
+                y_min=y_min,
+                y_max=y_max
+            )
+        )
+
+    if x_min < 0 or x_max >= width or y_min < 0 or y_max >= height:
+        raise ValueError(
+            'Values for crop should be non negative and smaller than image sizes'
+            '(x_min = {x_min}, y_min = {y_min}, x_max = {x_max}, y_max = {y_max}'
+            'height = {height}, width = {width})'.format(
+                x_min=x_min,
+                x_max=x_max,
+                y_min=y_min,
+                y_max=y_max,
+                height=height,
+                width=width
+            )
+        )
+
+    return img[y_min:y_max, x_min:x_max]
+
+
 def center_crop(img, crop_height, crop_width):
     height, width = img.shape[:2]
     if height < crop_height or width < crop_width:

albumentations/augmentations/transforms.py

@@ -11,7 +11,7 @@
            'RandomRotate90', 'Rotate', 'ShiftScaleRotate', 'CenterCrop', 'OpticalDistortion', 'GridDistortion',
            'ElasticTransform', 'HueSaturationValue', 'PadIfNeeded', 'RGBShift', 'RandomBrightness', 'RandomContrast',
            'MotionBlur', 'MedianBlur', 'GaussNoise', 'CLAHE', 'ChannelShuffle', 'InvertImg', 'ToGray',
-           'JpegCompression', 'Cutout', 'ToFloat', 'FromFloat']
+           'JpegCompression', 'Cutout', 'ToFloat', 'FromFloat', 'Crop']
 
 
 class PadIfNeeded(DualTransform):
@@ -26,7 +26,6 @@ class PadIfNeeded(DualTransform):
     Image types:
         uint8, float32
 
-    TODO: add application to boxes
     """
 
     def __init__(self, min_height=1024, min_width=1024, p=1.0):
@@ -41,6 +40,33 @@ def apply_to_bbox(self, bbox, **params):
         pass
 
 
+class Crop(DualTransform):
+    """Crops region from image
+
+    Args:
+        x_min (int): minimum upper left x coordinate
+        y_min (int): minimum upper left y coordinate
+        x_max (int): maximum lower right x coordinate
+        y_max (int): maximum lower right y coordinate
+
+    Targets:
+        image, mask
+
+    Image types:
+        uint8, float32
+    """
+
+    def __init__(self, x_min=0, y_min=0, x_max=1024, y_max=1024, p=1.0):
+        super(Crop, self).__init__(p)
+        self.x_min = x_min
+        self.y_min = y_min
+        self.x_max = x_max
+        self.y_max = y_max
+
+    def apply(self, img, **params):
+        return F.crop(img, x_min=self.x_min, y_min=self.y_min, x_max=self.x_max, y_max=self.y_max)
+
+
 class VerticalFlip(DualTransform):
     """Flips the input vertically around the x-axis.
 
@@ -296,6 +322,7 @@ class OpticalDistortion(DualTransform):
     Image types:
         uint8, float32
     """
+
     def __init__(self, distort_limit=0.05, shift_limit=0.05, interpolation=cv2.INTER_LINEAR,
                  border_mode=cv2.BORDER_REFLECT_101, p=0.5):
         super(OpticalDistortion, self).__init__(p)
@@ -321,6 +348,7 @@ class GridDistortion(DualTransform):
     Image types:
         uint8, float32
     """
+
     def __init__(self, num_steps=5, distort_limit=0.3, interpolation=cv2.INTER_LINEAR,
                  border_mode=cv2.BORDER_REFLECT_101, p=0.5):
         super(GridDistortion, self).__init__(p)
@@ -351,6 +379,7 @@ class ElasticTransform(DualTransform):
     Image types:
         uint8, float32
     """
+
     def __init__(self, alpha=1, sigma=50, alpha_affine=50, interpolation=cv2.INTER_LINEAR,
                  border_mode=cv2.BORDER_REFLECT_101, p=0.5):
         super(ElasticTransform, self).__init__(p)
@@ -633,6 +662,7 @@ class MedianBlur(Blur):
     Image types:
         uint8, float32
     """
+
     def __init__(self, blur_limit=7, p=0.5):
         super(MedianBlur, self).__init__(p)
         self.blur_limit = to_tuple(blur_limit, 3)

docs/probabilities.rst

@@ -8,7 +8,7 @@ About probabilities.
 Default probability values
 ******************************
 
-**Compose**, **PadIfNeeded**, **CenterCrop**, **RandomCrop**, **Normalize**, **ToFloat**, **FromFloat**, **ToTensor** have default
+**Compose**, **PadIfNeeded**, **CenterCrop**, **RandomCrop**, **Crop**, **Normalize**, **ToFloat**, **FromFloat**, **ToTensor** have default
 probability values equal to **1**. All other are equal to **0.5**