I'm working on some python programming and I need some help as to how to double the size of a picture using the image module.... any ideas?!

11 Years
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Last Post by vegaseat

Is the picture you are loading smaller than what you want to display? If yes, the quality will suffer quite a bit! The program has to make up missing information.

Are you using the Python Image Library PIL for this?


I know the quality will be degraded, but I'm going for making it larger either way.... and yes I'm using the PIL.... and yes I am going from smaller to larger.....


Here is what I have done... some steps i did may not have been necessary, for example the extra color variables.... though now i need help with my zoom factor.... because this works for zooming in two times... but when higher numbers come about it skips pixels... i messed around with an extra for loop but its still the same... any other ideals?

def enlarge(oImage,w,h,x,y,zoom):
    nImage= EmptyImage(w*zoom,h*zoom)
    for q in range(w):
        x = x +zoom
        y = 0
        for z in range(h):
            color = oImage.getPixel(q,z)
            red= color[0]
            green= color[1]
            blue= color[2]
            nImage.setPixel(x ,y ,(red,green,blue))
            nImage.setPixel(x+1,y +1,(red,green,blue))
            nImage.setPixel(x+1, y,(red,green,blue))
            nImage.setPixel(x, y+1,(red,green,blue))
            for lea in range(1,zoom):
                nImage.setPixel(x, y+lea,(red,green,blue))
                nImage.setPixel(x+lea,y, (red, green,blue))
            y = y +zoom
    r = nImage
    winner = ImageWin("Big Picture", w*zoom, h*zoom)

def main():
    picname= raw_input("Enter Picture name with .jpg, .bmp, or ending: ")
    oImage= FileImage(picname)
    h= oImage.getHeight()
    w= oImage.getWidth()
    win = ImageWin("Original", w,h)
    y = 0
    zoom = input("Number of times to zoom: ")
    x = -(zoom)




I need to refraise what i said... I need help being able to take a user input for the number of times to zoom in and put it into my program but I need help with the for loop in how to do it.... pixels are being skipped when i go in to higher numbers!


I remember in school they talked about DIB (device indepentant bitmaps) to be best for stretching/enlarging. Was C class for graph artists.


Meh.... yea... I don't know what you are talking about ... but yea... I just need help looping it to the point where its not skipping Pixels......


Need to import image(not Image).... so on the top needs to be "from image import * "


Yes it is........... it is attached... just resave it as a .py file (which you probably already knew to do)...... and you'll be set! I forgot it was a library we used for my comp sci class (this project was due 2 weeks ago.. but I'm just expanding on it is all!!!)

This module provides a simple interface to create a window, load an image and experiment 
with image based algorithms.  Many of which require pixel-by-pixel manipulation.  This
is a educational module, its not intended to replace the excellent Python Image Library, in fact 
it uses PIL.

The module and its interface and some of the code were inspired/copied by/from John Zelle's graphics.py 
which serves a similar purpose in the graphics primitive world.

import Tkinter
import Image
import ImageTk

# Borrow some ideas from Zelle
# create an invisible global main root for all windows
tk = Tkinter
_root = tk.Tk()

class ImageWin(tk.Canvas):
    ImageWin:  Make a frame to display one or more images.
    def __init__(self,title,width,height):        
        Create a window with a title, width and height.
        master = tk.Toplevel(_root)
        master.protocol("WM_DELETE_WINDOW", self.close)
        tk.Canvas.__init__(self, master, width=width, height=height)
        self.foreground = "black"
        self.items = []
        self.mouseX = None
        self.mouseY = None
        self.bind("<Button-1>", self._onClick)
        self.height = height
        self.width = width
        self._mouseCallback = None
        self.trans = None

    def close(self):
        """Close the window"""
    def getMouse(self):
        """Wait for mouse click and return a tuple with x,y position in screen coordinates after
        the click"""
        self.mouseX = None
        self.mouseY = None
        while self.mouseX == None or self.mouseY == None:
        return ((self.mouseX,self.mouseY))

    def setMouseHandler(self, func):
        self._mouseCallback = func

    def _onClick(self, e):
        self.mouseX = e.x
        self.mouseY = e.y
        if self._mouseCallback:
            self._mouseCallback(Point(e.x, e.y)) 
class image:
    Create an image.  The image may be created in one of four ways:
    1. From an image file such as gif, jpg, png, ppm  for example: i = image('fname.jpb)
    2. From a list of lists
    3. From another image object
    4. By specifying the height and width to create a blank image.
    imageCache = {} # tk photoimages go here to avoid GC while drawn 
    imageId = 1
    def __init__(self,fname=None,data=[],imobj=None,height=0,width=0):
        An image can be created using any of the following keyword parameters. When image creation is 
        complete the image will be an rgb image.
        fname:  A filename containing an image.  Can be jpg, gif, and others
        data:  a list of lists representing the image.  This might be something you construct by
        reading an asii format ppm file, or an ascii art file and translate into rgb yourself.
        imobj:  Make a copy of another image.
        width: Create a blank image of a particular height and width.
        if fname:
            self.im = Image.open(fname)
            ni = self.im.convert("RGB")
            self.im = ni
        elif data:
            height = len(data)
            width = len(data[0])
            self.im = Image.new("RGB",(width,height))
            for row  in range(height):
                for col in range(width):
        elif height > 0 and width > 0:
            self.im = Image.new("RGB",(width,height))
        elif imobj:
            self.im = imobj.copy()
        self.width,self.height = self.im.size
        self.centerX = self.width/2
        self.centerY = self.height/2
        self.id = None

    def copy(self):
        """Return a copy of this image"""
        newI = image(imobj=self.im)
        return newI

    def clone(self):
	     """Return a copy of this image"""
	     newI = image(imobj=self.im)
	     return newI
    def getHeight(self):
        """Return the height of the image"""
        return self.height

    def getWidth(self):
        """Return the width of the iamge"""
        return self.width
    def getPixel(self,x,y):
        """Get a pixel at the given x,y coordinate.  The pixel is returned as an rgb color tuple
        for eaxamplle foo.getPixel(10,10) --> (10,200,156) """
        return self.im.getpixel((x,y))
    def setPixel(self,x,y,colorTuple):
        """Set the color of a pixel at position x,y.  The color must be specified as an rgb tuple (r,g,b) where 
        the rgb values are between 0 and 255."""
    def setPosition(self,x,y):
        """Set the position in the window where the center of this image should be."""
        self.centerX = x
        self.centerY = y
    def draw(self,win):
        """Draw this image in the ImageWin window."""
        ig = ImageTk.PhotoImage(self.im)
        self.imageCache[self.imageId] = ig # save a reference else Tk loses it...
        image.imageId = image.imageId + 1
        self.id = self.canvas.create_image(self.centerX,self.centerY,image=ig)

class FileImage(image):
	def __init__(self,thefile):
		image.__init__(self,fname = thefile)
class EmptyImage(image):
	def __init__(self,cols,rows):
		image.__init__(self,height = rows, width = cols)
class ListImage(image):
	def __init__(self,thelist):

# Example program  Read in an image and calulate the negative.
if __name__ == '__main__':
    win = ImageWin("My Window",480,640)
    oImage = image('lcastle.jpg')
    myImage = oImage.copy()

    for row in range(myImage.getHeight()):
        for col in range(myImage.getWidth()):
             v = myImage.getPixel(col,row)
             x = map(lambda x: 255-x, v)

is there anyone else who could take a look at this module and mess around with what i have? thanks


I did manage to test your code and found the problem. With zoom > 3 you will have to expand the code accordingly ...

# double the size of an image attempt

from image import *

def enlarge(oImage, w, h, x, y, zoom):
    nImage = EmptyImage(w*zoom, h*zoom)
    for q in range(w):
        x = x + zoom
        y = 0

        for z in range(h):
            color = oImage.getPixel(q, z)
            #print x, y, q, z, color  # test
            red = color[0]
            green = color[1]
            blue = color[2]
            # this takes care of zoom=2
            nImage.setPixel(x , y, (red, green, blue))
            nImage.setPixel(x+1, y+1, (red, green, blue))
            nImage.setPixel(x+1, y, (red, green, blue))
            nImage.setPixel(x, y+1, (red, green, blue))
            if zoom > 2:
                # problem here, skips pixel loacations and defaults to black (0,0,0)
                # (x+2,y+1) and (x+1,y+2) are skipped on zoom = 3
                # even more pixels are skipped on zoom = 4
                for lea in range(2, zoom):
                    #print lea,  # test
                    nImage.setPixel(x+lea, y+lea, (red,green,blue))
                    nImage.setPixel(x, y+lea, (red, green, blue))
                    nImage.setPixel(x+1, y+lea, (red, green, blue))  # added for zoom=3
                    nImage.setPixel(x+lea, y, (red, green, blue))
                    nImage.setPixel(x+lea, y+1, (red, green, blue))  # added for zoom=3
            y = y + zoom

    r = nImage
    winner = ImageWin("Big Picture", w*zoom, h*zoom)

def main():
    #picname= raw_input("Enter Picture name with .jpg, .bmp, or ending: ")
    picname = "white80x80.jpg"  # uses a totally white 80x80 test jpeg
    oImage = FileImage(picname)
    h = oImage.getHeight()
    w = oImage.getWidth()
    win = ImageWin("Original", w, h)
    zoom = input("Number of times to zoom: ")
    zoom = 3  # added for testing
    x = -zoom
    y = 0

    enlarge(oImage, w, h, x, y, zoom)


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