j2me drawChar abnormal character spacing? - java-me

I write some code to draw a text on a j2me canvas without using drawString.
For some reasons I can't use drawString method.
So, when I run my program, I deal with abnormal character spacing.
Please help me to solve the problem. This is my code:
public void paint(Graphics g) {
...
String str = ... ;
int x0 = 10;
int y0 = getHeight() - 50;
Font f = g.getFont();
int charWidth = 0;
for (int i = 0; i < str.length(); i++) {
char ch = str.charAt(i);
charWidth = f.charWidth(ch);
x0 += charWidth;
g.drawChar(ch, x0, y0, 0);
}
...
}

instead use this:
public void paint(Graphics g) {
...
String str = ... ;
int x0 = 10;
int y0 = getHeight() - 50;
Font f = g.getFont();
int lastWidth = 0;
for (int i = 0; i < str.length(); i++) {
char ch = str.charAt(i);
g.drawChar(ch, x0 + lastWidth, y0, 0);
lastWidth += f.charWidth(ch);
}
...
}
In your drawChar method,you use 0(it is equal to Graphics.TOP|Graphics.LEFT) so you would increase "lastWidth" after draw current char,or use another anchor(for example Graphics.TOP|Graphics.RIGHT) for drawChar.

Related

CS50 pset4 filter reflection

#include "helpers.h"
#include <math.h>
// Convert image to grayscale
void grayscale(int height, int width, RGBTRIPLE image[height][width])
{
for ( int h=0 ; h<height ; h++)
{
for (int w=0 ; w<width ; w++)
{
int i = image[h][w].rgbtBlue + image[h][w].rgbtGreen + image[h][w].rgbtRed ;
float j = i/3 ;
int n = round(j) ;
image[h][w].rgbtBlue = n ;
image[h][w].rgbtGreen = n ;
image[h][w].rgbtRed = n ;
}
}
return;
}
// Convert image to sepia
void sepia(int height, int width, RGBTRIPLE image[height][width])
{
for ( int h=0 ; h<height ; h++)
{
for (int w=0 ; w<width ; w++)
{
float sr = .393 * image[h][w].rgbtRed + .769 * image[h][w].rgbtGreen + .189 * image[h][w].rgbtBlue ;
float sg = .349 * image[h][w].rgbtRed + .686 * image[h][w].rgbtGreen + .168 * image[h][w].rgbtBlue ;
float sb = .272 * image[h][w].rgbtRed + .534 * image[h][w].rgbtGreen + .131 * image[h][w].rgbtBlue ;
int SR = round(sr);
int SG = round(sg);
int SB = round(sb);
if ( SR>255)
{
SR = 255 ;
}
if (SG>255)
{
SG = 255 ;
}
if (SB>255)
{
SB = 255 ;
}
image[h][w].rgbtBlue = SB ;
image[h][w].rgbtGreen = SG ;
image[h][w].rgbtRed = SR ;
}
}
return;
}
// Reflect image horizontally
void swap (int *a , int *b) ;
void reflect(int height, int width, RGBTRIPLE image[height][width])
{
for (int h=0 ; h<height ; h++)
{
for (int w=0 ; w<width/2 ; w++)
{
for (int p=width-1 ; p>=round(width/2) ; p--)
{
int blue = image[h][w].rgbtBlue ;
int B = image[h][p].rgbtBlue ;
swap(&blue , &B);
int g = image[h][w].rgbtGreen ;
int G = image[h][p].rgbtGreen ;
swap(&g , &G);
int r = image[h][w].rgbtRed ;
int R = image[h][p].rgbtRed ;
swap(&r , &R );
}
}
}
return;
}
void swap (int *a , int *b)
{
int tmp = *a ;
*a = *b ;
*b = tmp ;
}
// Blur image
void blur(int height, int width, RGBTRIPLE image[height][width])
{
return;
}
I have written this code for helper.c. It compiles ok and works for grayscale and sepia but fails to reflect the image.
I am stuck in it . Please tell me where have i made the mistake.
// Reflect image horizontally
void reflect(int height, int width, RGBTRIPLE image[height][width])
{
int tmp[3];
for (int h = 0; h < height; h++)
{
for (int w = 0; w < width / 2; w++)
{
// Place the first pixel in a temporary variable
tmp[0] = image[h][w].rgbtRed;
tmp[1] = image[h][w].rgbtGreen;
tmp[2] = image[h][w].rgbtBlue;
// Place the opposite pixel one into the first pixel
image[h][w].rgbtRed = image[h][width - w - 1].rgbtRed;
image[h][w].rgbtGreen = image[h][width - w - 1].rgbtGreen;
image[h][w].rgbtBlue = image[h][width - w - 1].rgbtBlue;
// From the temporary variable extract the first pixel and place it into
the opposite pixel
image[h][width - w - 1].rgbtRed = tmp[0];
image[h][width - w - 1].rgbtGreen = tmp[1];
image[h][width - w - 1].rgbtBlue = tmp[2];
}
}
return;
}
You don't need the third for loop
for (int p=width-1 ; p>=round(width/2) ; p--)
instead, you can assign the opposite pixel inside the second loop as follows:
for (int w=0 ; w<width/2 ; w++)
{
p = width - w - 1;
...
}

Reaction-Diffusion algorithm on Processing + Multithreading

I have made an implementation of the Reaction-Diffusion algorithm on Processing 3.1.1, following a video tutorial. I have made some adaptations on my code, like implementing it on a torus space, instead of a bounded box, like the video.
However, I ran into this annoying issue, that the code runs really slow, proportional to the canvas size (larger, slower). With that, I tried optmizing the code, according to my (limited) knowledge. The main thing I did was to reduce the number of loops running.
Even then, my code still ran quite slow.
Since I have noticed that with a canvas of 50 x 50 in size, the algorithm ran at a good speed, I tried making it multithreaded, in such a way that the canvas would be divided between the threads, and each thread would run the algorithm for a small region of the canvas.
All threads read from the current state of the canvas, and all write to the future state of the canvas. The canvas is then updated using Processing's pixel array.
However, even with multithreading, I didn't see any performance improvement. By the contrary, I saw it getting worse. Now sometimes the canvas flicker between a rendered state and completely white, and in some cases, it doesn't even render.
I'm quite sure that I'm doing something wrong, or I may be taking the wrong approach to optimizing this algorithm. And now, I'm asking for help to understand what I'm doing wrong, and how I could fix or improve my code.
Edit: Implementing ahead of time calculation and rendering using a buffer of PImage objects has removed flickering, but the calculation step on the background doesn't run fast enough to fill the buffer.
My Processing Sketch is below, and thanks in advance.
ArrayList<PImage> buffer = new ArrayList<PImage>();
Thread t;
Buffer b;
PImage currentImage;
Point[][] grid; //current state
Point[][] next; //future state
//Reaction-Diffusion algorithm parameters
final float dA = 1.0;
final float dB = 0.5;
//default: f = 0.055; k = 0.062
//mitosis: f = 0.0367; k = 0.0649
float feed = 0.055;
float kill = 0.062;
float dt = 1.0;
//multi-threading parameters to divide canvas
int threadSizeX = 50;
int threadSizeY = 50;
//red shading colors
color red = color(255, 0, 0);
color white = color(255, 255, 255);
color black = color(0, 0, 0);
//if redShader is false, rendering will use a simple grayscale mode
boolean redShader = true;
//simple class to hold chemicals A and B amounts
class Point
{
float a;
float b;
Point(float a, float b)
{
this.a = a;
this.b = b;
}
}
void setup()
{
size(300, 300);
//initialize matrices with A = 1 and B = 0
grid = new Point[width][];
next = new Point[width][];
for (int x = 0; x < width; x++)
{
grid[x] = new Point[height];
next[x] = new Point[height];
for (int y = 0; y < height; y++)
{
grid[x][y] = new Point(1.0, 0.0);
next[x][y] = new Point(1.0, 0.0);
}
}
int a = (int) random(1, 20); //seed some areas with B = 1.0
for (int amount = 0; amount < a; amount++)
{
int siz = 2;
int x = (int)random(width);
int y = (int)random(height);
for (int i = x - siz/2; i < x + siz/2; i++)
{
for (int j = y - siz/2; j < y + siz/2; j++)
{
int i2 = i;
int j2 = j;
if (i < 0)
{
i2 = width + i;
} else if (i >= width)
{
i2 = i - width;
}
if (j < 0)
{
j2 = height + j;
} else if (j >= height)
{
j2 = j - height;
}
grid[i2][j2].b = 1.0;
}
}
}
initializeThreads();
}
/**
* Divide canvas between threads
*/
void initializeThreads()
{
ArrayList<Reaction> reactions = new ArrayList<Reaction>();
for (int x1 = 0; x1 < width; x1 += threadSizeX)
{
for (int y1 = 0; y1 < height; y1 += threadSizeY)
{
int x2 = x1 + threadSizeX;
int y2 = y1 + threadSizeY;
if (x2 > width - 1)
{
x2 = width - 1;
}
if (y2 > height - 1)
{
y2 = height - 1;
}
Reaction r = new Reaction(x1, y1, x2, y2);
reactions.add(r);
}
}
b = new Buffer(reactions);
t = new Thread(b);
t.start();
}
void draw()
{
if (buffer.size() == 0)
{
return;
}
PImage i = buffer.get(0);
image(i, 0, 0);
buffer.remove(i);
//println(frameRate);
println(buffer.size());
//saveFrame("output/######.png");
}
/**
* Faster than calling built in pow() function
*/
float pow5(float x)
{
return x * x * x * x * x;
}
class Buffer implements Runnable
{
ArrayList<Reaction> reactions;
boolean calculating = false;
public Buffer(ArrayList<Reaction> reactions)
{
this.reactions = reactions;
}
public void run()
{
while (true)
{
if (buffer.size() < 1000)
{
calculate();
if (isDone())
{
buffer.add(currentImage);
Point[][] temp;
temp = grid;
grid = next;
next = temp;
calculating = false;
}
}
}
}
boolean isDone()
{
for (Reaction r : reactions)
{
if (!r.isDone())
{
return false;
}
}
return true;
}
void calculate()
{
if (calculating)
{
return;
}
currentImage = new PImage(width, height);
for (Reaction r : reactions)
{
r.calculate();
}
calculating = true;
}
}
class Reaction
{
int x1;
int x2;
int y1;
int y2;
Thread t;
public Reaction(int x1, int y1, int x2, int y2)
{
this.x1 = x1;
this.x2 = x2;
this.y1 = y1;
this.y2 = y2;
}
public void calculate()
{
Calculator c = new Calculator(x1, y1, x2, y2);
t = new Thread(c);
t.start();
}
public boolean isDone()
{
if (t.getState() == Thread.State.TERMINATED)
{
return true;
} else
{
return false;
}
}
}
class Calculator implements Runnable
{
int x1;
int x2;
int y1;
int y2;
//weights for calculating the Laplacian for A and B
final float[][] laplacianWeights = {{0.05, 0.2, 0.05},
{0.2, -1, 0.2},
{0.05, 0.2, 0.05}};
/**
* x1, x2, y1, y2 delimit a rectangle. The object will only work within it
*/
public Calculator(int x1, int y1, int x2, int y2)
{
this.x1 = x1;
this.x2 = x2;
this.y1 = y1;
this.y2 = y2;
//println("x1: " + x1 + ", y1: " + y1 + ", x2: " + x2 + ", y2: " + y2);
}
#Override
public void run()
{
reaction();
show();
}
public void reaction()
{
for (int x = x1; x <= x2; x++)
{
for (int y = y1; y <= y2; y++)
{
float a = grid[x][y].a;
float b = grid[x][y].b;
float[] l = laplaceAB(x, y);
float a2 = reactionDiffusionA(a, b, l[0]);
float b2 = reactionDiffusionB(a, b, l[1]);
next[x][y].a = a2;
next[x][y].b = b2;
}
}
}
float reactionDiffusionA(float a, float b, float lA)
{
return a + ((dA * lA) - (a * b * b) + (feed * (1 - a))) * dt;
}
float reactionDiffusionB(float a, float b, float lB)
{
return b + ((dB * lB) + (a * b * b) - ((kill + feed) * b)) * dt;
}
/**
* Calculates Laplacian for both A and B at same time, to reduce amount of loops executed
*/
float[] laplaceAB(int x, int y)
{
float[] l = {0.0, 0.0};
for (int i = x - 1; i < x + 2; i++)
{
for (int j = y - 1; j < y + 2; j++)
{
int i2 = i;
int j2 = j;
if (i < 0)
{
i2 = width + i;
} else if (i >= width)
{
i2 = i - width;
}
if (j < 0)
{
j2 = height + j;
} else if (j >= height)
{
j2 = j - height;
}
int weightX = (i - x) + 1;
int weightY = (j - y) + 1;
l[0] += laplacianWeights[weightX][weightY] * grid[i2][j2].a;
l[1] += laplacianWeights[weightX][weightY] * grid[i2][j2].b;
}
}
return l;
}
public void show()
{
currentImage.loadPixels();
//renders the canvas using the pixel array
for (int x = 0; x < width; x++)
{
for (int y = 0; y < height; y++)
{
float a = next[x][y].a;
float b = next[x][y].b;
int pix = x + y * width;
float diff = (a - b);
color c;
if (redShader) //aply red shading
{
float thresh = 0.5;
if (diff < thresh)
{
float diff2 = map(pow5(diff), 0, pow5(thresh), 0, 1);
c = lerpColor(black, red, diff2);
} else
{
float diff2 = map(1 - pow5(-diff + 1), 1 - pow5(-thresh + 1), 1, 0, 1);
c = lerpColor(red, white, diff2);
}
} else //apply gray scale shading
{
c = color(diff * 255, diff * 255, diff * 255);
}
currentImage.pixels[pix] = c;
}
}
currentImage.updatePixels();
}
}
A programmer had a problem. He thought “I know, I’ll solve it with threads!”. has Now problems. two he
Processing uses a single rendering thread.
It does this for good reason, and most other renderers do the same thing. In fact, I don't know of any multi-threaded renderers.
You should only change what's on the screen from Processing's main rendering thread. In other words, you should only change stuff from Processing's functions, not your own thread. This is what's causing the flickering you're seeing. You're changing stuff as it's being drawn to the screen, which is a horrible idea. (And it's why Processing uses a single rendering thread in the first place.)
You could try to use your multiple threads to do the processing, not the rendering. But I highly doubt that's going to be worth it, and like you saw, it might even make things worse.
If you want to speed up your sketch, you might also consider doing the processing ahead of time instead of in real time. Do all your calculations at the beginning of the sketch, and then just reference the results of the calculations when it's time to draw the frame. Or you could draw to a PImage ahead of time, and then just draw those.

I want to track 2 colours, but only record the movement of those two colours and hide the video feed

For context: I am going to analyze the breathing movement of parents during kangaroo mother care and I wish to respect their privacy by not recording them, but only the movement of stickers I placed on their chest and stomach.
So far, I'm able to track 2 colours based on webcam input through the code below. However, I would like to record only the tracked colours instead of the webcam feed as to preserve the privacy of the parent.
Does anybody know how to add a background colour, whilst still being able to track colour?
import processing.video.*;
Capture video;
final int TOLERANCE = 20;
float XRc = 0;// XY coordinate of the center of the first target
float YRc = 0;
float XRh = 0;// XY coordinate of the center of the second target
float YRh = 0;
int ii=0; //Mouse click counter
color trackColor; //The first color is the center of the robot
color trackColor2; //The second color is the head of the robot
void setup() {
size(640,480);
video = new Capture(this,640,480);
video.start();
trackColor = color(255,0,0);
trackColor2 = color(255,0,0);
smooth();
}
void draw() {
background(0);
if (video.available()) {
video.read();
}
video.loadPixels();
image(video,0,0);
float r2 = red(trackColor);
float g2 = green(trackColor);
float b2 = blue(trackColor);
float r3 = red(trackColor2);
float g3 = green(trackColor2);
float b3 = blue(trackColor2);
int somme_x = 0, somme_y = 0;
int compteur = 0;
int somme_x2 = 0, somme_y2 = 0;
int compteur2 = 0;
for(int x = 0; x < video.width; x++) {
for(int y = 0; y < video.height; y++) {
int currentLoc = x + y*video.width;
color currentColor = video.pixels[currentLoc];
float r1 = red(currentColor);
float g1 = green(currentColor);
float b1 = blue(currentColor);
if(dist(r1,g1,b1,r2,g2,b2) < TOLERANCE) {
somme_x += x;
somme_y += y;
compteur++;
}
else if(compteur > 0) {
XRc = somme_x / compteur;
YRc = somme_y / compteur;
}
if(dist(r1,g1,b1,r3,g3,b3) < TOLERANCE) {
somme_x2 += x;
somme_y2 += y;
compteur2++;
}
else if(compteur2 > 0) {
XRh = somme_x2 / compteur2;
YRh = somme_y2 / compteur2;
}
}
}
if(XRc != 0 || YRc != 0) { // Draw a circle at the first target
fill(trackColor);
strokeWeight(0.05);
stroke(0);
ellipse(XRc,YRc,20,20);
}
if(XRh != 0 || YRh != 0) {// Draw a circle at the second target
fill(trackColor2);
strokeWeight(0.05);
stroke(0);
ellipse(XRh,YRh,20,20);
}
}
void mousePressed() {
if (mousePressed && (mouseButton == RIGHT)) { // Save color where the mouse is clicked in trackColor variable
if(ii==0){
if (mouseY>480){mouseY=0;mouseX=0;}
int loc = mouseX + mouseY*video.width;
trackColor = video.pixels[loc];
ii=1;
}
else if(ii==1){
if (mouseY>480){mouseY=0;mouseX=0;}
int loc2 = mouseX + mouseY*video.width;
trackColor2 = video.pixels[loc2];
ii=2;
}
}
}
Try adding the background(0); right before you draw the first circle. It should cover the video and you can draw the circles on top of it.
Regards
Jose

How do you flatten image coordinates into a 1D array?

My source code is from Heterogeneous Computing with OpenCL Chapter 4 Basic OpenCL Examples > Image Rotation. The book leaves out several critical details.
My major problem is that I don't know how to initialize the array that I supply to their kernel (they don't tell you how). What I have is:
int W = inImage.width();
int H = inImage.height();
float *myImage = new float[W*H];
for(int row = 0; row < H; row++)
for(int col = 0; col < W; col++)
myImage[row*W+col] = col;
which I supply to this kernel:
__kernel void img_rotate(__global float* dest_data, __global float* src_data, int W, int H, float sinTheta, float cosTheta)
{
const int ix = get_global_id(0);
const int iy = get_global_id(1);
float x0 = W/2.0f;
float y0 = H/2.0f;
float xoff = ix-x0;
float yoff = iy-y0;
int xpos = (int)(xoff*cosTheta + yoff*sinTheta + x0);
int ypos = (int)(yoff*cosTheta - xoff*sinTheta + y0);
if(((int)xpos>=0) && ((int)xpos < W) && ((int)ypos>=0) && ((int)ypos<H))
{
dest_data[iy*W+ix] = src_data[ypos*W+xpos];
//dest_data[iy*W+ix] = src_data[iy*W+ix];
}
}
I'm having trouble finding the right value for theta too. An integer would be an appropriate value for theta, right?
float theta = 45; // 45 degrees, right?
float cos_theta = cos(theta);
float sin_theta = sin(theta);
When writing my OpenCL code, I always treat each kernel as reading a 3D set of data, regardless if the data is 1D, 2D, or 3D:
__kernel void TestKernel(__global float *Data){
k = get_global_id(0); //also z
j = get_global_id(1); //also y
i = get_global_id(2); //also x
//Convert 3D to 1D
int linear_coord = i + get_global_size(0)*j + get_global_size(0)*get_global_size(1)*k;
//do stuff
}
When doing the clEnqueueNDKernelRange(...), just set the dimension to be:
int X = 500;
int Y = 300;
int Z = 1;
size_t GlobalDim = {Z, Y, X};
This let's all of my kernels work easily in all dimensions.

Lanczos Resampling error

I have written an image resizer using Lanczos re-sampling. I've taken the implementation straight from the directions on wikipedia. The results look good visually, but for some reason it does not match the result from Matlab's resize with Lanczos very well (in pixel error).
Does anybody see any errors? This is not my area of expertise at all...
Here is my filter (I'm using Lanczos3 by default):
double lanczos_size_ = 3.0;
inline double sinc(double x) {
double pi = 3.1415926;
x = (x * pi);
if (x < 0.01 && x > -0.01)
return 1.0 + x*x*(-1.0/6.0 + x*x*1.0/120.0);
return sin(x)/x;
}
inline double LanczosFilter(double x) {
if (std::abs(x) < lanczos_size_) {
double pi = 3.1415926;
return sinc(x)*sinc(x/lanczos_size_);
} else {
return 0.0;
}
}
And my code to resize the image:
Image Resize(Image& image, int new_rows, int new_cols) {
int old_cols = image.size().cols;
int old_rows = image.size().rows;
double col_ratio =
static_cast<double>(old_cols)/static_cast<double>(new_cols);
double row_ratio =
static_cast<double>(old_rows)/static_cast<double>(new_rows);
// Apply filter first in width, then in height.
Image horiz_image(new_cols, old_rows);
for (int r = 0; r < old_rows; r++) {
for (int c = 0; c < new_cols; c++) {
// x is the new col in terms of the old col coordinates.
double x = static_cast<double>(c)*col_ratio;
// The old col corresponding to the closest new col.
int floor_x = static_cast<int>(x);
horiz_image[r][c] = 0.0;
double weight = 0.0;
// Add up terms across the filter.
for (int i = floor_x - lanczos_size_ + 1; i < floor_x + lanczos_size_; i++) {
if (i >= 0 && i < old_cols) {
double lanc_term = LanczosFilter(x - i);
horiz_image[r][c] += image[r][i]*lanc_term;
weight += lanc_term;
}
}
// Normalize the filter.
horiz_image[r][c] /= weight;
// Strap the pixel values to valid values.
horiz_image[r][c] = (horiz_image[r][c] > 1.0) ? 1.0 : horiz_image[r][c];
horiz_image[r][c] = (horiz_image[r][c] < 0.0) ? 0.0 : horiz_image[r][c];
}
}
// Now apply a vertical filter to the horiz image.
Image new_image(new_cols, new_rows);
for (int r = 0; r < new_rows; r++) {
double x = static_cast<double>(r)*row_ratio;
int floor_x = static_cast<int>(x);
for (int c = 0; c < new_cols; c++) {
new_image[r][c] = 0.0;
double weight = 0.0;
for (int i = floor_x - lanczos_size_ + 1; i < floor_x + lanczos_size_; i++) {
if (i >= 0 && i < old_rows) {
double lanc_term = LanczosFilter(x - i);
new_image[r][c] += horiz_image[i][c]*lanc_term;
weight += lanc_term;
}
}
new_image[r][c] /= weight;
new_image[r][c] = (new_image[r][c] > 1.0) ? 1.0 : new_image[r][c];
new_image[r][c] = (new_image[r][c] < 0.0) ? 0.0 : new_image[r][c];
}
}
return new_image;
}
Here is Lanczosh in one single loop. no errors.
Uses mentioned at top procedures.
void ResizeDD(
double* const pixelsSrc,
const int old_cols,
const int old_rows,
double* const pixelsTarget,
int const new_rows, int const new_cols)
{
double col_ratio =
static_cast<double>(old_cols) / static_cast<double>(new_cols);
double row_ratio =
static_cast<double>(old_rows) / static_cast<double>(new_rows);
// Now apply a filter to the image.
for (int r = 0; r < new_rows; ++r)
{
const double row_within = static_cast<double>(r)* row_ratio;
int floor_row = static_cast<int>(row_within);
for (int c = 0; c < new_cols; ++c)
{
// x is the new col in terms of the old col coordinates.
double col_within = static_cast<double>(c)* col_ratio;
// The old col corresponding to the closest new col.
int floor_col = static_cast<int>(col_within);
double& v_toSet = pixelsTarget[r * new_cols + c];
v_toSet = 0.0;
double weight = 0.0;
for (int i = floor_row - lanczos_size_ + 1; i <= floor_row + lanczos_size_; ++i)
{
for (int j = floor_col - lanczos_size_ + 1; j <= floor_col + lanczos_size_; ++j)
{
if (i >= 0 && i < old_rows && j >= 0 && j < old_cols)
{
const double lanc_term = LanczosFilter(row_within - i + col_within - j);
v_toSet += pixelsSrc[i * old_rows + j] * lanc_term;
weight += lanc_term;
}
}
}
v_toSet /= weight;
v_toSet = (v_toSet > 1.0) ? 1.0 : v_toSet;
v_toSet = (v_toSet < 0.0) ? 0.0 : v_toSet;
}
}
}
The line
for (int i = floor_x - lanczos_size_ + 1; i < floor_x + lanczos_size_; i++)
should be
for (int i = floor_x - lanczos_size_ + 1; i <= floor_x + lanczos_size_; i++)
Do not know but perhaps other mistakes linger too.
I think there is a mistake in your sinc function. Below the fraction bar you have to square pi and x. Additional you have to multiply the function with lanczos size
L(x) = **a***sin(pi*x)*sin(pi*x/a) * (pi**²**x**²**)^-1
Edit: My mistake, there is all right.

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