Zoom image to pixel level

Question

For an art project, one of the things I will do is scale the image to a specific pixel. I rubbed my chin and would like to advise how to proceed.

Here are the input parameters:

Screen:
sw - screen width
sh - screen height

Image:
iw - image width
ih - image height

Pixel:
px - x position of pixel in image
py - y position of pixel in image

Zoom:
zf - zoom factor (0.0 to 1.0)

Background colour:
bc - background colour to use when screen and image aspect ratios are different

Outputs:

The zoomed image (no anti-aliasing)
The screen position/dimensions of the pixel we are zooming to.

When zf is 0 the image must fit the screen with correct aspect ratio.
When zf is 1 the selected pixel fits the screen with correct aspect ratio.

One of my ideas was to use something like povray and move the camera towards a large image texture or some library (like pygame) to scale. Does anyone think of something smarter with a simple pseudo-code?

To make it simpler, you can make the image and screen the same. I can live with it.

I will update additional information as necessary.

UPDATE

Converted accepted answer in PHP

Image Pixel Zoom on GitHub

Answer 1

image[x][y]

image[x+zf*(px-x)][y+zf*(py-y)]

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Python -

def naivezoom(im, px, py, zf, bg):
    out = Image.new(im.mode, im.size)        
    pix = out.load()
    iw, ih = im.size
    for x in range(iw):
        for y in range(ih):
            xorg = x + zf*(px - x)
            yorg = y + zf*(py - y)
            if xorg >= 0 and xorg < iw and yorg >= 0 and yorg < ih:
                pix[x,y] = im.getpixel( (xorg , yorg) )
            else:
                pix[x,y] = bg
    return out

,

im = Image.open("filename.ext")

import Image

: stackoverflow

zf = 0,3, 25,6

zf = 0,96,

#!/bin/env python
from Tkinter import *
import Image
import ImageTk

def naivezoom(im, p, zf, bg):
    out = Image.new(im.mode, im.size)
    pix = out.load()
    iw, ih = im.size
    for x in range(iw):
        for y in range(ih):
            xorg = x + zf*(p[0] - x)
            yorg = y + zf*(p[1] - y)
            if xorg >= 0 and xorg < iw and yorg >= 0 and yorg < ih:
                pix[x,y] = im.getpixel( (xorg , yorg) )
            else:
                pix[x,y] = bg
    return out

class NaiveTkZoom:
    def __init__(self, parent=None):
        root = Tk()
        self.im = Image.open('logo.jpg')
        self.zf = 0.0
        self.deltazf = 0.02
        self.p = ( 0.1*self.im.size[0],0.1*self.im.size[1])
        self.bg = 255
        canvas = Canvas(root, width=self.im.size[0]+20 , height=self.im.size[1]+20)
        canvas.pack()
        root.bind('<Key>', self.onKey)
        self.canvas = canvas
        self.photo = ImageTk.PhotoImage(self.im)
        self.item = self.canvas.create_image(10, 10, anchor=NW, image=self.photo)
    def onKey(self, event):
        if event.char == "+":
            if self.zf < 1:
                self.zf += self.deltazf
        elif event.char == "-":
            if self.zf > 0:
                self.zf -= self.deltazf
        self.out = naivezoom(self.im, self.p, self.zf, self.bg)
        self.photo = ImageTk.PhotoImage(self.out)
        self.canvas.delete(self.item)
        self.item = self.canvas.create_image(10, 10, anchor=NW, image=self.photo)
        print self.p, self.zf

if __name__ == "__main__":
    NaiveTkZoom()
    mainloop()

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#!/bin/env python
from Tkinter import *
import Image
import ImageTk

def markImage(im, p, bg):
    pix = im.load()
    pix[ p[0], p[1] ] = bg

def naiveZoom(im, p, zf, bg):
    out = Image.new(im.mode, im.size)
    pix = out.load()
    iw, ih = im.size
    for x in range(iw):
        for y in range(ih):
            xorg = x + zf*(p[0]+0.5-x) + zf*(1-zf)*(p[0]-iw/2)
            yorg = y + zf*(p[1]+0.5-y) + zf*(1-zf)*(p[1]-ih/2)
            if xorg >= 0 and xorg < iw and yorg >= 0 and yorg < ih:
                pix[x,y] = im.getpixel( (xorg , yorg) )
            else:
                pix[x,y] = bg
    return out

class NaiveTkZoom:
    def __init__(self, parent=None):
        root = Tk()
        self.im = Image.open('py.jpg')
        self.zf = 0.0
        self.deltazf = 0.05
        self.p = (round(0.3*self.im.size[0]), round(0.3*self.im.size[1]) )
        self.bg = 255
        markImage(self.im, self.p, self.bg)
        canvas = Canvas(root, width=self.im.size[0]+20 , height=self.im.size[1]+20)
        canvas.pack()
        root.bind('<Key>', self.onKey)
        self.canvas = canvas
        self.photo = ImageTk.PhotoImage(self.im)
        self.item = self.canvas.create_image(10, 10, anchor=NW, image=self.photo)
        self.change = False
    def onKey(self, event):
        if event.char == "+":
            if self.zf < 1:
                self.zf += self.deltazf
                self.change = True
        elif event.char == "-":
            if self.zf > 0:
                self.zf -= self.deltazf
                self.change = True
        if self.change:
            self.out = naiveZoom(self.im, self.p, self.zf, self.bg)
            self.photo = ImageTk.PhotoImage(self.out)   
            self.canvas.delete(self.item)
            self.change = False
        self.item = self.canvas.create_image(10, 10, anchor=NW, image=self.photo)
        print self.p, self.zf

if __name__ == "__main__":
    NaiveTkZoom()
    mainloop()

. :)

Answer 2

. - : Processing

1D, :

, :

D (x) = a x + b

:

z = 0: D (px) = px D (px + 1) = px + 1

z = 1: D (px) = 0 D (px + 1) = sw

:

z = 0: a = 1, b = 0, D (x) = x

z = 1: a = sw, b = -sw. px, D (x) = sw.x - sw.px

z :

D (x) = z (sw.x - sw.px) + (1 - z) (x) D (x) = (z.sw + 1 - z).x - z.sw.px

:

ID (xout) = (xout + z.sw.px)/(z.sw + 1 - z)

. OriginalPixel [ID (xout)] ( ID (xout) [0..sw], )

2D , .

Answer 3

, . (, Gimp), 1 . .. mencoder AVI .