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2018-08-13 image data processng

2018-08-13 image data processng

作者: 镜中无我 | 来源:发表于2019-02-18 17:15 被阅读4次

pretreatment

TFRecord

input data format
Example{Features{map<String,Feature{BytesList or FloatList or Int64List}>}}
write

  • step1: setup a writer with filename for TFRecord
  • step2: get the images data ,labels data ,and etc.
  • step3: piecewise transformation{
    setup a example with image-concerned data
    write its serialized sequence into writer
    }
    read
  • step1: setup a reader with filepath
  • step2: read the serialized example
  • step3: parse_single_example(serialized_example,features={'': tf.FixedLenFeature([],tf.dtype,...)})
  • step4: images= tf.decode_raw(features['image_raw'], tf.uint8)
    other cast(features,dtype)
  • step5: multi threads for processing
image processing functions
  • encoding
    objects: jpeg png
image_raw_data=tf.gfile.FastGFile('image_path','r').read()
with tf.session() as sess:
       img_data=tf.image.decode_jpeg(image_raw_data)
       print(img_data.eval())
       plt.imshow(img_data.eval())
       plt.show()
       img_data=tf.image_convert_iamge_dtype(img_data,dtype=tf.float32)
#encode 
  • scale adjustment
    tf.image.resize_images(img_data, 300,300,method=0)
    method:
    method value algorithms
    0 Bilinear interpolation
    1 Nearest neighbor interpolation
    2 Bicubic interpolation
    3 Area interpolation

tf.image.resize_image_with_crop_or_pad(img_data, len_scale,wid_scale)
tf.image.central_crop(img_data,proportion)
tf.image.flip_up_down(...)#left_right
tf.image.transpose_image(image_data)
tf.image.random_flip_...

  • color
    tf.image.adjust_brightness(img_data,-0.5)
    tf.image.random_brightness(img_data,max_delta)
    tf.image.adjust_contrast(img_data,-5)
    tf.image.random_contrast(...,lower,upper)
    tf.image.adjust_hue(image_data,)#0.1,0.3,0.6,0.9
    tf.image.random_hue(,max_delta)
    tf.image.adjust_saturation(...,...,...)
    tf.image.per_image_whitening(...)#standardize the image
  • marking frame
    tf.image.draw_bounding_boxes(img_data,coordinates of boxes)

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