coco.py

import os
from tqdm import trange
from PIL import Image, ImageOps, ImageFilter
import numpy as np
import torch

from .base import BaseDataset

"""
NUM_CHANNEL = 91
[] background
[5] airplane
[2] bicycle
[16] bird
[9] boat
[44] bottle
[6] bus
[3] car
[17] cat
[62] chair
[21] cow
[67] dining table
[18] dog
[19] horse
[4] motorcycle
[1] person
[64] potted plant
[20] sheep
[63] couch
[7] train
[72] tv
"""
CAT_LIST = [0, 5, 2, 16, 9, 44, 6, 3, 17, 62, 21, 67, 18, 19, 4,
    1, 64, 20, 63, 7, 72]


class COCOSegmentation(BaseDataset):
    def __init__(self, root=os.path.expanduser('~/.encoding/data'), split='train',
                 mode=None, transform=None, target_transform=None):
        super(COCOSegmentation, self).__init__(
            root, split, mode, transform, target_transform)
        from pycocotools.coco import COCO
        from pycocotools import mask
        if mode == 'train':
            print('train set')
            ann_file = os.path.join(root, 'coco/annotations/instances_train2014.json')
            ids_file = os.path.join(root, 'coco/annotations/train_ids.pth')
            root = os.path.join(root, 'coco/train2014')
        else:
            print('val set')
            ann_file = os.path.join(root, 'coco/annotations/instances_val2014.json')
            ids_file = os.path.join(root, 'coco/annotations/val_ids.pth')
            root = os.path.join(root, 'coco/val2014')
        self.coco = COCO(ann_file)
        self.coco_mask = mask
        if os.path.exists(ids_file):
            self.ids = torch.load(ids_file)
        else:
            ids = list(self.coco.imgs.keys())
            self.ids = self._preprocess(ids, ids_file)
        self.transform = transform
        self.target_transform = target_transform

    def __getitem__(self, index):
        coco = self.coco
        img_id = self.ids[index]
        img_metadata = coco.loadImgs(img_id)[0]
        path = img_metadata['file_name']
        img = Image.open(os.path.join(self.root, path)).convert('RGB')
        cocotarget = coco.loadAnns(coco.getAnnIds(imgIds=img_id))
        mask = Image.fromarray(self._gen_seg_mask(cocotarget, img_metadata['height'], 
                               img_metadata['width']))
        # synchrosized transform
        if self.mode == 'train':
            img, mask = self._sync_transform(img, mask)
        elif self.mode == 'val':
            img, mask = self._val_sync_transform(img, mask)
        else:
            assert self.mode == 'testval'
            mask = self._mask_transform(mask)
        # general resize, normalize and toTensor
        if self.transform is not None:
            img = self.transform(img)
        if self.target_transform is not None:
            mask = self.target_transform(mask)
        return img, mask

    def __len__(self):
        return len(self.ids)

    def _gen_seg_mask(self, target, h, w):
        mask = np.zeros((h, w), dtype=np.uint8)
        coco_mask = self.coco_mask
        for instance in target:
            rle = coco_mask.frPyObjects(instance['segmentation'], h, w)
            m = coco_mask.decode(rle)
            cat = instance['category_id']
            if cat in CAT_LIST:
                c = CAT_LIST.index(cat)
            else:
                continue
            if len(m.shape) < 3:
                mask[:, :] += (mask == 0) * (m * c)
            else:
                mask[:, :] += (mask == 0) * (((np.sum(m, axis=2)) > 0) * c).astype(np.uint8)
        return mask

    def _preprocess(self, ids, ids_file):
        print("Preprocessing mask, this will take a while." + \
            "But don't worry, it only run once for each split.")
        tbar = trange(len(ids))
        new_ids = []
        for i in tbar:
            img_id = ids[i]
            cocotarget = self.coco.loadAnns(self.coco.getAnnIds(imgIds=img_id))
            img_metadata = self.coco.loadImgs(img_id)[0]
            mask = self._gen_seg_mask(cocotarget, img_metadata['height'], 
                                      img_metadata['width'])
            # more than 1k pixels
            if (mask > 0).sum() > 1000:
                new_ids.append(img_id)
            tbar.set_description('Doing: {}/{}, got {} qualified images'.\
                format(i, len(ids), len(new_ids)))
        print('Found number of qualified images: ', len(new_ids))
        torch.save(new_ids, ids_file)
        return new_ids