Related
I was analyzing a 12 bit per pixel, GRBG, Little Endian, 1920x1280 resolution raw image but I am confused how data or RGB pixels are stored. Image size is 4915200 bytes, when calculated 4915200/(1920x1280) = 2. That means each pixel takes 2 bytes and 4 bits in 2bytes are used for padding. I tried to edit image with Hex editor but I have no idea how pixels are stored in image. Please do share if you have any idea.
Image Link
That means each pixel takes 2 bytes and 4 bits in 2bytes are used for padding
Well, sort of. It means each sample is stored in two consecutive bytes, with 4 bits of padding. But in raw images, samples usually aren't pixels, not exactly. Raw images have not been demosaiced yet, they are raw after all. For GRGB, the Bayer pattern looks like this:
What's in the file, is a 1920x1280 grid of 12+4 bit samples, arranged in the same order as pixels would have been, but each sample has only one channel, namely the one that corresponds to its position in the Bayer pattern.
Additionally, the color space is probably linear, not Gamma-compressed. The color balance is unknown unless you reverse engineer it. A proper decoder would have a calibrated color matrix, but I don't have that.
I combined these two things and guessed a color balance to do a really basic decoding (with bad demosaicing, just to demonstrate that the above information is probably accurate):
Using this C# code:
Bitmap bm = new Bitmap(1920, 1280);
for (int y = 0; y < 1280; y += 2)
{
int i = y * 1920 * 2;
for (int x = 0; x < 1920; x += 2)
{
const int stride = 1920 * 2;
int d0 = data[i] + (data[i + 1] << 8);
int d1 = data[i + 2] + (data[i + 3] << 8);
int d2 = data[i + stride] + (data[i + stride + 1] << 8);
int d3 = data[i + stride + 2] + (data[i + stride + 3] << 8);
i += 4;
int r = Math.Min((int)(Math.Sqrt(d1) * 4.5), 255);
int b = Math.Min((int)(Math.Sqrt(d2) * 9), 255);
int g0 = Math.Min((int)(Math.Sqrt(d0) * 5), 255);
int g3 = Math.Min((int)(Math.Sqrt(d3) * 5), 255);
int g1 = Math.Min((int)(Math.Sqrt((d0 + d3) * 0.5) * 5), 255);
bm.SetPixel(x, y, Color.FromArgb(r, g0, b));
bm.SetPixel(x + 1, y, Color.FromArgb(r, g1, b));
bm.SetPixel(x, y + 1, Color.FromArgb(r, g1, b));
bm.SetPixel(x + 1, y + 1, Color.FromArgb(r, g3, b));
}
}
You can load your image into a Numpy array and reshape correctly like this:
import numpy as np
# Load image and reshape
img = np.fromfile('Image_12bpp_grbg_LittleEndian_1920x1280.raw',dtype=np.uint16).reshape((1280,1920))
print(img.shape)
(1280, 1920)
Then you can demosaic and scale to get a 16-bit PNG. Note that I don't know your calibration coefficients so I guessed:
#!/usr/bin/env python3
# Demosaicing Bayer Raw image
# https://stackoverflow.com/a/68823014/2836621
import cv2
import numpy as np
filename = 'Image_12bpp_grbg_LittleEndian_1920x1280.raw'
# Set width and height
w, h = 1920, 1280
# Read mosaiced image as GRGRGR...
# BGBGBG...
bayer = np.fromfile(filename, dtype=np.uint16).reshape((h,w))
# Extract g0, g1, b, r from mosaic
g0 = bayer[0::2, 0::2] # every second pixel down and across starting at 0,0
g1 = bayer[1::2, 1::2] # every second pixel down and across starting at 1,1
r = bayer[0::2, 1::2] # every second pixel down and across starting at 0,1
b = bayer[1::2, 0::2] # every second pixel down and across starting at 1,0
# Apply (guessed) color matrix for 16-bit PNG
R = np.sqrt(r) * 1200
B = np.sqrt(b) * 2300
G = np.sqrt((g0+g1)/2) * 1300 # very crude
# Stack into 3 channel
BGR16 = np.dstack((B,G,R)).astype(np.uint16)
# Save result as 16-bit PNG
cv2.imwrite('result.png', BGR16)
Keywords: Python, raw, image processing, Bayer, de-Bayer, mosaic, demosaic, de-mosaic, GBRG, 12-bit.
How can I paste back a part of my picture after I changed it in MATLAB? I cropped the plates off this image of a car and now I want to put it back automatically. The plates are still at the same coordinates as they were initially, but the background is all black.
The car I want to paste on:
And this is what I want to paste:
Here is my code, I want to change the part where I need to draw by hand the plate.
fontSize = 20;
format compact;
baseFileName1 = 'blurr_plate.jpg';
baseFileName2 = 'car2.jpg';
sourceImage = imread(baseFileName1);
subplot(1, 2, 1);
imshow(sourceImage);
axis on;
caption = sprintf('Source image, %s', baseFileName1);
title(caption, 'FontSize', fontSize, 'Interpreter', 'none');
% Enlarge figure to full screen.
set(gcf, 'units','normalized','outerposition',[0 0 1 1]);
% Give a name to the title bar.
set(gcf,'name','Demo by ImageAnalyst','numbertitle','off')
targetImage = imread(baseFileName2);
subplot(1, 2, 2);
imshow(targetImage);
axis on;
caption = sprintf('Target image, %s, original', baseFileName2);
title(caption, 'FontSize', fontSize, 'Interpreter', 'none');
% Ask user to draw freehand mask.
message = sprintf('In the LEFT IMAGE...\nLeft click and hold to begin drawing.\nSimply lift the mouse button to finish');
subplot(1, 2, 1);
uiwait(msgbox(message));
hFH = imfreehand(); % Actual line of code to do the drawing.
% Create a binary image ("mask") from the ROI object.
mask = hFH.createMask();
xy = hFH.getPosition;
% Paste it onto the target image.
targetImage(mask) = sourceImage(mask);
% Display new image.
subplot(1, 2, 2); % Switch active axes to right hand axes.
imshow(targetImage);
imwrite(targetImage, 'car_new.jpg')
axis on;
caption = sprintf('Target image, %s, after paste', baseFileName2);
title(caption, 'FontSize', fontSize, 'Interpreter', 'none');
Your code will work only in case when both source and target images are grayscale. As your target image is coloured, make following changes:
Delete line number 35,36 and 41.
paste this code after line 33.
redChannel = targetImage(:, :, 1);
greenChannel = targetImage(:, :, 2);
blueChannel = targetImage(:, :, 3);
redChannel(mask) = sourceImage(mask);
greenChannel(mask) = sourceImage(mask);
blueChannel(mask) = sourceImage(mask);
targetImage = cat(3, redChannel, greenChannel, blueChannel);
I would like to overlap two images, one grayscale and one RGB image. I would like to impose the RGB image on top of the grayscale image, but ONLY for pixels greater than a certain value. I tried using the double function in MATLAB, but this seems to change the color scheme and I cannot recover the original RGB colors. What should I do in order to retain the original RGB image instead of mapping it to one of the MATLAB colormaps? Below is my attempt at superimposing:
pixelvalues = double(imread('hello.png'));
PixelInt = mean(pixelvalues,3);
I1 = ind2rgb(Brightfield(:,:,1), gray(256)); %Brightfield
I2 = ind2rgb(PixelInt, jet(256)); %RGB Image
imshow(I2,[])
[r,c,d] = size(I2);
I1 = I1(1:r,1:c,1:d);
% Replacing those pixels below threshold with Brightfield Image
threshold = 70;
I2R = I2(:,:,1); I2G = I2(:,:,2); I2B = I2(:,:,3);
I1R = I1(:,:,1); I1G = I1(:,:,2); I1B = I1(:,:,3);
I2R(PixelInt<threshold) = I1R(PixelInt<threshold);
I2G(PixelInt<threshold) = I1G(PixelInt<threshold);
I2B(PixelInt<threshold) = I1B(PixelInt<threshold);
I2(:,:,1) = I2R; I2(:,:,2) = I2G; I2(:,:,3) = I2B;
h = figure;
imshow(I2,[])
Original RGB Image:
Brightfield:
Overlay:
Is the content of pixelvalues what you show in your first image? If so, that image does not use a jet colormap. It has pink and white values above the red values, whereas jet stops at dark red at the upper limits. When you take the mean of those values and then generate a new RGB image with ind2rgb using the jet colormap, you're creating an inherently different image. You probably want to use pixelvalues directly in generating your overlay, like so:
% Load/create your starting images:
pixelvalues = imread('hello.png'); % Color overlay
I1 = repmat(Brightfield(:, :, 1), [1 1 3]); % Grayscale underlay
[r, c, d] = size(pixelvalues);
I1 = I1(1:r, 1:c, 1:d);
% Create image mask:
PixelInt = mean(double(pixelvalues), 3);
threshold = 70;
mask = repmat((PixelInt > threshold), [1 1 3]);
% Combine images:
I1(mask) = pixelvalues(mask);
imshow(I1);
Note that you may need to do some type conversions when loading/creating the starting images. I'm assuming 'hello.png' is a uint8 RGB image and Brightfield is of type uint8. If I load your first image as pixelvalues and your second image as I1, I get the following when running the above code:
Create a mask and use it to combine the images:
onionOrig = imread('onion.png');
onionGray = rgb2gray(onionOrig);
onionMask = ~(onionOrig(:,:,1)<100 & onionOrig(:,:,2)<100 & onionOrig(:,:,3)<100);
onionMasked(:,:,1) = double(onionOrig(:,:,1)) .* onionMask + double(onionGray) .* ~onionMask;
onionMasked(:,:,2) = double(onionOrig(:,:,2)) .* onionMask + double(onionGray) .* ~onionMask;
onionMasked(:,:,3) = double(onionOrig(:,:,3)) .* onionMask + double(onionGray) .* ~onionMask;
onionFinal = uint8(onionMasked);
imshow(onionFinal)
I'm trying to convert an image with many circles with the same center, from Cartesian to Polar (so that the new image will be the circles but lines instead of the circles, see the image below), and that's working out just fine using the following code:
[r, c] = size(img);
r=floor(r/2);
c=floor(c/2);
[X, Y] = meshgrid(-c:c-1,-r:r-1);
[theta, rho] = cart2pol(X, Y);
subplot(221), imshow(img), axis on;
hold on;
subplot(221), plot(xCenter,yCenter, 'r+');
subplot(222), warp(theta, rho, zeros(size(theta)), img);
view(2), axis square;
The problem is, I don't understand why does it even work? (obviously it's not my code), I mean, when I use the function cart2pol I don't even use the image, it's just some vectors x and y generated from the meshgrid function..
and another problem is, I want somehow to have a new image (not just to be able to draw it with the wrap function) which is the original image but by the theta and rho coordinates (meaning the same pixels but rearranged)... I'm not even sure how to ask this, in the end I want to have an image which is a matrix so that I can sum each row and turn the matrix into a column vector...
You can think of your image as being a 2D matrix, where each pixel has an X and Y coordinate
[(1,1) (1,2) (1,3) .... (1,c)]
[(2,1) (2,2) (2,3) .... (2,c)]
[(3,1) (3,2) (3,3) .... (3,c)]
[.... .... .... .... .... ]
[(r,1) (r,2) (r,3) .... (r,c)]
In the code that you posted, it maps each of these (X,Y) coordinates to it's equivalent polar coordinate (R, theta) using the center of the image floor(c/2) and floor(r/2) as the reference point.
% Map pixel value at (1,1) to it's polar equivalent
[r,theta] = cart2pol(1 - floor(r/2),1 - floor(c/2));
So whatever pixel value was used for (1,1) should now appear in your new polar coordinate space at (r,theta). It is important to note that to do this conversion, no information about the actual pixel values in the image matters, rather we just want to perform this transformation for each pixel within the image.
So first we figure out where the center of the image is:
[r, c] = size(img);
r = floor(r / 2);
c = floor(c / 2);
Then we figure out the (X,Y) coordinates for every point in the image (after the center has already been subtracted out
[X, Y] = meshgrid(-c:c-1,-r:r-1);
Now convert all of these cartesian points to polar coordinates
[theta, rho] = cart2pol(X, Y);
All that warp now does, is say "display the value of img at (X,Y) at it's corresponding location in (theta, rho)"
warp(theta, rho, zeros(size(theta)), img);
Now it seems that you want a new 2D image where the dimensions are [nTheta, nRho]. To do this, you could use griddata to interpolate your scattered (theta, rho) image (which is displayed by warp above) to a regular grid.
% These is the spacing of your radius axis (columns)
rhoRange = linspace(0, max(rho(:)), 100);
% This is the spacing of your theta axis (rows)
thetaRange = linspace(-pi, pi, 100);
% Generate a grid of all (theta, rho) coordinates in your destination image
[T,R] = meshgrid(thetaRange, rhoRange);
% Now map the values in img to your new image domain
theta_rho_image = griddata(theta, rho, double(img), T, R);
Take a look at all the interpolation methods for griddata to figure out which is most appropriate for your scenario.
There were a couple other issues (like the rounding of the center) which caused the result to be slightly incorrect. A fully working example is provided below
% Create an image of circles
radii = linspace(0, 40, 10);
rows = 100;
cols = 100;
img = zeros(rows, cols);
for k = 1:numel(radii)
t = linspace(0, 2*pi, 1000);
xx = round((cos(t) * radii(k)) + (cols / 2));
yy = round((sin(t) * radii(k)) + (rows / 2));
toremove = xx > cols | xx < 1 | yy > rows | yy < 1;
inds = sub2ind(size(img), xx(~toremove), yy(~toremove));
img(inds) = 1;
end
[r,c] = size(img);
center_row = r / 2;
center_col = c / 2;
[X,Y] = meshgrid((1:c) - center_col, (1:r) - center_row);
[theta, rho] = cart2pol(X, Y);
rhoRange = linspace(0, max(rho(:)), 1000);
thetaRange = linspace(-pi, pi, 1000);
[T, R] = meshgrid(thetaRange, rhoRange);
theta_rho_image = griddata(theta, rho, double(img), T, R);
figure
subplot(1,2,1);
imshow(img);
title('Original Image')
subplot(1,2,2);
imshow(theta_rho_image);
title('Polar Image')
And the result
I am trying to paste multiple smaller images (9 rectangles of different sizes) onto a black background. The center horizontal line of each of these images should be aligned and all the edges should be touching. It doesn't matter where on the black it is pasted as long as they are aligned as described. I will attach some images of what I mean.
example of a smaller image
http://i.imgur.com/Dlu6es4.png
desired result
http://i.imgur.com/ujuhCWs.png
ImageAnalyst provided this great code for pasting images, but I think what I need is a bit more complicated. If anybody can help out or point me to a good direction, I would be very grateful. Many thanks!
if true
% % Lets user drag out a box on an image, then define where they want to paste it.
% Then it pastes the drawn region onto the original image.
% Figure out how to select two points for pasting
clc; % Clear the command window.
close all; % Close all figures (except those of imtool.)
imtool close all; % Close all imtool figures.
clear; % Erase all existing variables.
workspace; % Make sure the workspace panel is showing.
fontSize = 20;
format compact;
grayImage = imread('Blackout.png');
% Get the dimensions of the image.
% numberOfColorBands should be = 1.
[rows columns numberOfColorBands] = size(grayImage);
% Display the original gray scale image.
subplot(2, 2, 1);
imshow(grayImage);
axis on;
title('Original Grayscale Image', 'FontSize', fontSize);
% Enlarge figure to full screen.
set(gcf, 'units','normalized','outerposition',[0 0 1 1]);
% Display the cropped image.
rotatedImage=imread('rotatedImage.png');
subplot(2, 2, 3);
imshow(rotatedImage);
axis on;
title('Region that you defined', 'FontSize', fontSize);
% Paste it onto the original image
[rows2 columns2] = size(rotatedImage)
promptMessage = sprintf('Click on the upper left point where you want to paste it,\nor Cancel to abort processing?');
titleBarCaption = 'Continue?';
button = questdlg(promptMessage, titleBarCaption, 'Continue', 'Cancel', 'Continue');
if strcmpi(button, 'Cancel')
return;
end
[x, y] = ginput(1)%pick 1 two-dimensional points from the figure and returns x y coordinates.
% Determine the pasting boundaries.
r1 = int32(y);
c1 = int32(x);
r2 = r1 + rows2 - 1;
r2 = min([r2 rows]);
c2 = c1 + columns2 - 1;
c2 = min([c2, columns]);
plot([c1 c2 c2 c1 c1], [r1 r1 r2 r2 r1], 'r-');
% Paste as much of croppedImage as will fit into the original image.
grayImage(r1:r2, c1:c2) = rotatedImage(1:(r2-r1+1), 1:(c2-c1+1));
subplot(2, 2, 4);
imshow(grayImage);
axis on;
title('Region that you defined pasted onto original', 'FontSize', fontSize);
%save rotated image
imwrite(grayImage, 'alignedImage.png');
Actually, I think I've figured it out! Just use the row sizes of each of the images to determine the placement of the next image. It's a little messy but I think it's a good start :)
% Lets user drag out a box on an image, then define where they want to paste it.
% Then it pastes the drawn region onto the original image.
% Figure out how to select two points for pasting
clc; % Clear the command window.
close all; % Close all figures (except those of imtool.)
imtool close all; % Close all imtool figures.
clear; % Erase all existing variables.
workspace; % Make sure the workspace panel is showing.
fontSize = 20;
format compact;
%%
grayImage = imread('Blackout.png');
% Get the dimensions of the image.
% numberOfColorBands should be = 1.
[I1R I1C numberOfColorBands] = size(grayImage);
% Display the original gray scale image.
subplot(1, 3, 1);
imshow(grayImage);
axis on;
title('Original Grayscale Image', 'FontSize', fontSize);
% Enlarge figure to full screen.
set(gcf, 'units','normalized','outerposition',[0 0 1 1]);
%%
% Display the cropped image.
rotatedImage=imread('rotCoxa.png');
subplot(1, 3, 2);
imshow(rotatedImage);
axis on;
title('Region that you defined', 'FontSize', fontSize);
% Paste it onto the original image
[I2R I2C] = size(rotatedImage);
%%
x = 1;
y = I1R/2;
% Determine the pasting boundaries.
r1 = int32(y);
c1 = int32(x);
r2 = r1 + I2R - 1;
r2 = min([r2 I1R]);
c2 = c1 + I2C - 1;
c2 = min([c2, I1R]);
plot([c1 c2 c2 c1 c1], [r1 r1 r2 r2 r1], 'r-');
% Paste as much of croppedImage as will fit into the original image.
grayImage(r1:r2, c1:c2) = rotatedImage(1:(r2-r1+1), 1:(c2-c1+1));
subplot(1, 3, 3);
imshow(grayImage);
axis on;
title('Region that you defined pasted onto original', 'FontSize', fontSize);
%%
%save rotated image
imwrite(grayImage, 'alignedImage.png');
%%
clc; % Clear the command window.
close all; % Close all figures (except those of imtool.)
imtool close all; % Close all imtool figures.
clear; % Erase all existing variables.
workspace; % Make sure the workspace panel is showing.
fontSize = 20;
format compact;
%%
%delete('Blackout.png');
grayImage = imread('alignedImage.png');
% Get the dimensions of the image.
% numberOfColorBands should be = 1.
[I1R I1C numberOfColorBands] = size(grayImage);
% Display the original gray scale image.
subplot(1, 3, 1);
imshow(grayImage);
axis on;
title('Original Grayscale Image', 'FontSize', fontSize);
% Enlarge figure to full screen.
set(gcf, 'units','normalized','outerposition',[0 0 1 1]);
%%
% Display the cropped image.
rotatedImage=imread('rotTrochanter.png');
subplot(1, 3, 2);
imshow(rotatedImage);
axis on;
title('Region that you defined', 'FontSize', fontSize);
% Paste it onto the original image
[I3R I3C] = size(rotatedImage);
%%
previouslyrotatedImage=imread('rotCoxa.png');
[I2R I2C] = size(previouslyrotatedImage);
x = I2C;
y = I1R/2 + I2R/2 - I3R; %check math. I3R/2 or I3R?
% Determine the pasting boundaries.
r1 = int32(y);
c1 = int32(x);
r2 = r1 + I3R - 1;
r2 = min([r2 I1R]);
c2 = c1 + I3C - 1;
c2 = min([c2, I1C]);
plot([c1 c2 c2 c1 c1], [r1 r1 r2 r2 r1], 'r-');
% Paste as much of croppedImage as will fit into the original image.
grayImage(r1:r2, c1:c2) = rotatedImage(1:(r2-r1+1), 1:(c2-c1+1));
subplot(1, 3, 3);
imshow(grayImage);
axis on;
title('Region that you defined pasted onto original', 'FontSize', fontSize);
%%
%save rotated image
imwrite(grayImage, 'alignedImage.png');