make thumnail befor save Image file

utils.py

def handle_uploaded_image(i, x, y):
    import StringIO
    from PIL import Image, ImageOps
    import os
    from django.core.files.images import ImageFile
    from django.core.files.uploadedfile import  InMemoryUploadedFile
    import uuid


    IMAGE_TYPE=i.content_type

    #PIL_TYPE use to save disk, FILE_EXTENSTION use to make the path
    print
    if IMAGE_TYPE =='image/jpeg':
         PIL_TYPE = 'image/jpg'
         PIL_SAVE = 'JPEG'
         FILE_EXTENSION = 'jpg'
    elif IMAGE_TYPE=='image/png':
        PIL_TYPE = 'image/png'
        PIL_SAVE = 'PNG'
        FILE_EXTENSION = 'png'
    else :
        raise Exception('Image-type-error', "It's not jpeg of PNG")


    #read image from InMemoryUploadedFile
    image_str = ""
    for c in i.chunks():
        image_str +=c

    #create PIL image instance
    imagefile = StringIO.StringIO(image_str)
    image = Image.open(imagefile)

    # if not RGB, convert
    if image.mode not in ("L", "RGB"):
        image = image.convert("RGB")

    width, height = image.size

    max_width = x
    max_height = y

    target_ratio = float(max_width)/float(max_height)
    ratio = float(width)/float(height)

    target_width = 0
    target_height = 0

    if (ratio>target_ratio):
        target_width = max_width
        target_height = int(target_width/ratio)
    else:
        target_height = max_height
        target_width = int(ratio * target_height)

    #resize(doing a thumb)
    if target_width < width or target_height < height:
        image = image.resize((target_width, target_height), Image.ANTIALIAS)



    #re-initialize imageFile and set a hash (unique filename)
    imagefile = StringIO.StringIO()
    filename = str(uuid.uuid1())+"."+FILE_EXTENSION

    #PIL instance(image) change to imagefile
    #return FILE instance after just resize not save
    thumnail_io= StringIO.StringIO()
    image.save(thumnail_io, format=PIL_SAVE)
    thumnail_io.seek(0)

    content = InMemoryUploadedFile(thumnail_io, None, filename, PIL_TYPE,
                                   thumnail_io.len, None)

    return (filename, content)