I would like to plot a scatter plot over a background image. But the origin of the image is at the top left corner. I need the bottom left of the image to be the origin so the bottom left = (0, 0.75) and top right (14, 1.25)
So I need to scale the image to my data from pH 0 - 14 (This is the x axis) and Eh 0.75 - 1.25 (This is the y axis)
Eh = [327.06 561.34 506.82 602.58 745.02 745.04 ...
693.96 682.9 648.46 468 412.18 522.94 459.74]./1e3; % V
pH = [6.4 4.51 5.08 4.98 3.63 4.31 6.24 6.22 4.94 6.44 7.05 5.09 4.63]; %pH
I=imread('Fe_Pourbaix.png');
xImg = linspace(0, 14, size(I, 2));
yImg = linspace(-0.75, 1.25, size(I, 1));
image(xImg, yImg, I, 'CDataMapping', 'scale');
hold on;
plot(pH, Eh,'*','LineWidth',2);
grid on;
Suppose I Need to flip the data? The below image is what I need is the x and y I need to produce to overlay my data
Related
So I currently have a screen with a width of 1080 pixels. I also have a camera, centered in the middle of the screen. The camera gives me the position on a screen as a value between 0 and 1. This way, when the width of the screen is multiplied by the position, you get its placement in the screen window. See below:
so the old is
0 , .5, 1 <-- The position in the screen (X)
0, 540, 1080 <-- The screen size (Y)
X*Y = Pixel Placement
However, I would like to crop off some of the camera so it corresponds more accurately to my screen. The new is:
.25, .5, .75 <-- (X)
0, 540, 1080 <-- (Y)
What is the equation for calculating this placement? I feel like I've learned this but forgotten the method. Thanks.
You have linear relationship
Y = Yleft + (X - Xleft) * (Yright - Yleft) / (Xright - Xleft)
For your example values
Yleft = 0
Yright = 1080
Xleft = 0.25
Xright = 0.75
so
Y = (X - 0.25) * 1080 / 0.5 = 2160 * (X - 0.25)
for X = 0.5
Y = 2160 * (0.5-0.25) = 540
I've got a project where I'm designing an image viewer for tiled images. Every image tile is 256x256 pixels. For each level of scaling, I'm increasing the size of each image by 5%. I represent the placement of the tiles by dividing the screen into tiles the same size as each image. An offset is used to precicely place each image where needed. When the scaling reaches a certain point(1.5), I switch over to a new layer of images that altogether has a greater resolution than the previous images. The zooming method itself looks like this:
def zoomer(self, mouse_pos, zoom_in): #(tuple, bool)
x, y = mouse_pos
x_tile, y_tile = x / self.tile_size, y / self.tile_size
old_scale = self.scale
if self.scale > 0.75 and self.scale < 1.5:
if zoom_in:
self.scale += SCALE_STEP # SCALE_STEP = 5% = 0.05
ratio = (SCALE_STEP + 1)
else:
self.scale -= SCALE_STEP
ratio = 1 / (SCALE_STEP + 1)
else:
if zoom_in:
self.zoom += 1
self.scale = 0.8
ratio = (SCALE_STEP + 1)
else:
self.zoom -= 1
self.scale = 1.45
ratio = 1 / (SCALE_STEP + 1)
# Results in x/y lengths of the relevant full image
x_len = self.size_list[self.levels][0] / self.power()
y_len = self.size_list[self.levels][1] / self.power()
# Removing extra pixel if present
x_len = x_len - (x_len % 2)
y_len = y_len - (y_len % 2)
# The tile's picture coordinates
tile_x = self.origo_tile[0] + x_tile
tile_y = self.origo_tile[1] + y_tile
# The mouse's picture pixel address
x_pic_pos = (tile_x * self.tile_size) -
self.img_x_offset + (x % self.tile_size)
y_pic_pos = (tile_y * self.tile_size) -
self.img_y_offset + (y % self.tile_size)
# Mouse percentile placement within the image
mouse_x_percent = (x_pic_pos / old_scale) / x_len
mouse_y_percent = (y_pic_pos / old_scale) / y_len
# The mouse's new picture pixel address
new_x = (x_len * self.scale) * mouse_x_percent
new_y = (y_len * self.scale) * mouse_y_percent
# Scaling tile size
self.tile_size = int(TILE_SIZE * self.scale)
# New mouse screen tile position
new_mouse_x_tile = x / self.tile_size
new_mouse_y_tile = y / self.tile_size
# The mouse's new tile address
new_tile_x = new_x / self.tile_size
new_tile_y = new_y / self.tile_size
# New tile offsets
self.img_x_offset = (x % self.tile_size) - int(new_x % self.tile_size)
self.img_y_offset = (y % self.tile_size) - int(new_y % self.tile_size)
# New origo tile
self.origo_tile = (int(new_tile_x) - new_mouse_x_tile,
int(new_tile_y) - new_mouse_y_tile)
Now, the issue arising from this is that the mouse_.._percent variables never seem to match up with the real position. For testing purposes, I feed the method with a mouse position centered in the middle of the screen and the picture centered in the middle too. As such, the resulting mouse_.._percent variable should, in a perfect world, always equal 50%. For the first level, it does, but quickly wanders off when scaling. By the time I reach the first zoom breakpoint (self.scale == 1.5), the position has drifted to x = 48%, y = 42%.
The self.origo_tile is a tuple containing the x/y coordinate for the tile to be drawn on screen tile (0, 0)
I've been staring at this for hours, but can't seen to find a remedy for it...
How the program works:
I apologize that I didn't have enough time to apply this to your code, but I wrote the following zooming simulator. The program allows you to zoom the same "image" multiple times, and it outputs the point of the image that would appear in the center of the screen, along with how much of the image is being shown.
The code:
from __future__ import division #double underscores, defense against the sinister integer division
width=256 #original image size
height=256
posx=128 #original display center, relative to the image
posy=128
while 1:
print "Display width: ", width
print "Display height: ", height
print "Center X: ", posx
print "Center Y: ", posy
anchx = int(raw_input("Anchor X: "))
anchy = int(raw_input("Anchor Y: "))
zmag = int(raw_input("Zoom Percent (0-inf): "))
zmag /= 100 #convert from percent to decimal
zmag = 1/zmag
width *= zmag
height *= zmag
posx = ((anchx-posx)*zmag)+posx
posy = ((anchy-posy)*zmag)+posy
Sample output:
If this program outputs the following:
Display width: 32.0
Display height: 32.0
Center X: 72.0
Center Y: 72.0
Explanation:
This means the zoomed-in screen shows only a part of the image, that part being 32x32 pixels, and the center of that part being at the coordinates (72,72). This means on both axes it is displaying pixels 56 - 88 of the image in this specific example.
Solution/Conclusion:
Play around with that program a bit, and see if you can implement it into your own code. Keep in mind that different programs move the Center X and Y differently, change the program I gave if you do not like how it works already (though you probably will, it's a common way of doing it). Happy Coding!
I want to change the size and position of my map colorbar. When I try to change the size and location of the colorbar, it is distorted in shape, I don't know why. Can anybody kindly help me. Please guide me why the set command distorts the clorbar? The location of the color bar should be 'southoutside'.The code is as under:
clear all,close all,clc
ax = worldmap('world');
load geoid
R = georasterref('RasterSize',[180 360],'Latlim',[-90 90],'Lonlim', [0 360]);
levels = [-70 -40 -20 -10 0 10 20 40 70];
geoshow(geoid, R, 'DisplayType', 'contour','LevelList',levels,'Fill','on','LineColor','black')
coast = load('coast.mat');
geoshow(coast.lat, coast.long, 'Color', 'white', 'LineWidth', 1.5)
cb = contourcbar('peer',ax,'Location','southoutside');
caxis([-110 90])
colormap(hsv)
set(get(cb,'XLabel'),'String','Geoid Undulation in Meters')
a=get(cb); %gets properties of colorbar
a.Position %gets the positon and size of the color bar
set(cb,'Position',[0.10 0.20 0.80 0.08])% To change size and position
What I would like to do is plot an image of a graph (from say a pdf file or a scanned image). Next, I would like to overlay an axis on the graph in the image, and then plot data on that axis (over the image).
Using imtool, I know the coordinates of the graph in the image (x range = ~52-355 pixels, and y range = 23(top) - 262(bottom) pixels in this case).
This is what I have tried:
I = imread('C:\MATLAB\R2014a\help\images\ref\ftrans2_fig.png');
I = squeeze(uint8(mean(I,3)));
figure, imshow(I)
[rows, cols] = size(I);
x_data = (-1 : .01 : +1)';
y_data = 1 - x_data.^2;
h1 = axes('Position',([52, 23, 355-52, 262-23] ./ [cols, rows, cols, rows] ));
set(h1, 'Color', 'none')
hold on
plot(x_data, y_data, '-rx')
Question: Knowing the pixel coordinates of the graph in the image, how do I determine the proper position of the axis in the figure, (my code fails to account for the actual size of the figure box, the gray border around the image). I have to do this for several images and sets of data, so I would like an automated method, assuming I find the coordinates of the graphs in the image ahead of time.
Thanks for your reply! (1st time posting, please be kind)
You may be able to solve your problem by forcing the image onto the same axis as the plot. Try this:
I = imread('C:\MATLAB\R2014a\help\images\ref\ftrans2_fig.png');
I = squeeze(uint8(mean(I,3)));
[rows, cols] = size(I);
x_data = (-1 : .01 : +1)';
y_data = 1 - x_data.^2;
h1 = axes('Position',([52, 23, 355-52, 262-23] ./ [cols, rows, cols, rows] ));
set(h1, 'Color', 'none')
hold on
image(I, 'Parent', h1);
plot(h1, x_data, y_data, '-rx')
That should at ensure that the plot axis and the image axis have the same origin, as they will be one and the same. You may need to adjust your sizing code. Let me know if that doesn't do it for you.
Good Luck!
I think I have it figured out.
It would have been easier if I could use:
figure, h1=imshow(I)
get(h1,'Position')
but that results in "The name 'Position' is not an accessible property for an instance of class 'image'."
Instead, this appears to work:
I = imread('C:\MATLAB\R2014a\help\images\ref\ftrans2_fig.png');
I = squeeze(uint8(mean(I,3)));
in_mag = 300;
figure, imshow(I, 'Border', 'tight', 'InitialMagnification', in_mag)
[rows, cols] = size(I);
x_data = (-1 : .01 : +1)';
y_data = 1 - x_data.^2;
% Coord of graph in image pixels
x_0 = 50; x_max = 354; y_0 = 262; y_max = 23;
h1 = axes('Position',([x_0, rows-y_0, x_max-x_0, y_0-y_max] ...
./ [cols, rows, cols, rows] ));
set(h1,'Color','none')
hold on
plot(x_data, y_data, '-rx')
ylim([0,1.4])
set(gca,'YColor', [0 0 1], 'XColor', [0 0 1])
However, if anybody has a better idea, I would be very happy to explore it!
Thanks
I have the following code which shows an image called zero.
I would like just to overlay a mask image (only 0 and 1 values) of the same dimensions so that 0 values are transparent (and then we can see the values of the zero image) and 1 values are shown in black.
What could I do?
hFig = figure(1);
set(hFig, 'Position', [11 11 27 7.5]);
set( gca, 'Units', 'normalized', 'Position', [0.05 0.05 0.93 1.2] );
set(0,'defaultFigureUnits','centimeters');
m_proj('equidistant cylindrical','longitudes',[-15 21],'latitudes',[11.5 18]);
m_gridF('ytick',4,'tickdir','out','ticklen',0.005,'linestyle','none');
hold; Plat=18-[0:13]*0.5;
Plon=-15+[0:72]*0.5;
[Plg,Plt]=meshgrid(Plon,Plat);
m_pcolor(Plg,Plt,zero);shading flat;
hold on;
polarmap(flipud(polarmap),0)
M=m_shaperead('clip');
for k=1:length(M.ncst),
m_line(M.ncst{k}(:,1),M.ncst{k}(:,2),'color','k');
end
hold;
h=colorbar('SouthOutside');
set(h, 'Position', [0.13 .1 .78 .05]);
set(get(h,'title'),'string','test','fontsize',14)
hold;