after doing PSF photometry with fixed stars using photutils I display the residual image and some stars are not fully removed. I tried saving the residual_image to a fits file to inspect it better but the resultant fits file has little boxes with the stars PSF in the position of the original star.
Do you know how can I save the residual_image to a fits file without including the inspected stars?
Here is the piece of code saving the image:
residual_image = photometry.get_residual_image()
fits.writeto('psf_residual.fits',data=residual_image,overwrite=True)
Here is a section of the resultant image:
https://i.stack.imgur.com/TP3IE.png
Solved.
After many tries, I discovered that the sigma I was using for the PSF model was too large, I was thinking it was too small [insert facepalm here].
Related
I have lots of high resolution image files that have regions of colors, basically blobs with different rgb values. I need to go through the images and for every image make a text file that contains the coordinates to one pixel in every blob. Because I have so many files the script needs to be fast. I already wrote some scala code to do the task except it only saves locations for one blob per specific RGB value, meaning if I have two blobs of the same color that are not connected it will only save one the location for the first one found. The solution to this is for each images copy the location and colors to a map and when I find a blob flood delete (flood fill except delete instead of fill) and then keep parsing on the new map. However, I think this will make run time horribly slow because I will have to go through the entire image to add it to a map before even starting the parse. Thoughts? Am I going about this all wrong?
Thanks.
I am working with MATLAB for a school project. The assignment is to import a matrix file supplied to me, and display it as a new figure using image. Right now, I can make an image with
m1 = load('matrix1.csv'); image(m1)
But the image is rotated to the right. How do I rotate it so the image is presented horizontally rather than vertically?
Your issue is likely arising from the fact that there are different ways of storing data (row-major vs. column-major). In this case, your .csv file clearly is not in the format you are expecting. The easiest thing to do is to simply transpose the matrix containing your data:
m1 = m1';
image(m1);
If there is something crazier going on and this flips it the wrong way (I don't think this should be the case, but you never know), you can try the rotate command: http://www.mathworks.com/help/matlab/ref/rot90.html
I'm very new to Matlab, though I know a few other programming languages, so please forgive me if this is something simple. I have not been able to find any answers to this, either on StackOverflow or elsewhere.
I produce a figure using the following code:
figure(6),imageplot(P); drawnow;
Which looks like this:
I then save this image to my computer using the following commands:
imwrite(P, 'images/plot.png');
And the resulting image is tiny, and missing some of the color information:
If, however, I utilize the save function in the open figure (image #1) and save it manually, I get exactly what I want, which is that exact image stored on my computer.
How would I program that? I assumed that imwrite() would just write the image directly, but apparently I'm doing something wrong. Any advice? Perhaps it has something to do with the imageplot command? I cannot seem to get that to work in imwrite.
Update: Based on the comments below, I have begun using "imresize" with the "nearest" option. This scales the image properly, but the resulting image is still curiously darker (and therefore has less information) than if I hit the "save" button in the figure.
Image saved from figure:
Image using "imresize" with "nearest" option:
The MATLAB imwrite command saves exactly the number of pixels as specified in your image matrix. This is the actual result of your computation; the reason the output is "tiny" is because it is supposed to be. To make it larger, would be to simply scale/zoom it as required.
The save figure option however does something quite different: it rasterizes the the output you obtain in the figure window and gives you the option for saving it as an image. This is evident in the fact that when you do so, you obtain a white background in addition to your result which is really just the grey background you see before you save it; this can be adjusted by resizing the figure window before utilizing the save option.
If you're looking to simply make the output figure larger, I would recommend using something along the lines of the imresize command.
Say, if you want the default size to be twice the size of the real result, simply use:
imresize(P, 2.0);
For more options, try help imresize.
The command you need for the "Save As..." functionality of figures is called "print". I often use
print(gcf, '-dpng', 'some_filename.png')
or
print(gcf, '-depsc', 'some_filename.eps','-r0')
to save a figure as it is shown on screen. The format png offers a small filesize and excellent quality, and it is understood by most image viewers and browsers. The eps format is a vector format, which I use for printig. The '-r0' option specifies "use the same size as given by the screen resolution" for the vector format properties.
I have a simple code to show an image in Matlab. I use imread() to read it and imshow() to show it. the code it below, and the result in not shown properly. hope someone can help me.
img = imread('/home/samuelpedro/Desktop/API - Projecto/coimbra_aerea.jpg');
figure, imshow(img);
the resulting image is below.
also, if i choose to save it to file as a new jpg it is saved correctly.
UPDATE 1:
weirdly if i choose to show the axes in the preferences>image processing, it is corrected
Locking at your screen-shot, the x- and y-ticks are missing. They should appear in a standard-configuration of Matlab. Maybe something is just messed up in the Matlab-configuration. Try to do this with a clean new ~/.matlab folder (rename the old one before).
Alternatively ... again judging by your screen-shot, this looks like Ubuntu/Unity in the background. Unity needs acceleration (OpenGL), which can be randomly buggy for some Linux graphics drivers. You may want to try to launch matlab in a "clean" X-server (maybe the twm environment) to rule this out.
Save the image as an (uncompressed) bitmap (bmp) and read it with imread. If the jpg is messed up by the imread-routine, this should rule this out.
Last but not least, broken copy of your jpg on your disk, some flipped bits. Run md5sums on your file's copies.
I have a 2D color-map plot created with imagesc and want to export it as a .eps file using
print -depsc.
The problem is that the "original" image data is from a rather small matrix (131 x 131). When I view the image in the matlab figure window, I can see all the individual pixels if I zoom a bit closer.
When I export to eps, however, there seems to be some interpolation or anti-aliasing going on, in that neighboring pixels get blurred/blended into each other. I don't get the problem if I export a high-resolution tiff, but that format is not an option (as demanded by a publisher).
How can I obtain an eps that preserves the pixely structure of my image without applying interpolation or anti-aliasing?
The blurring actually depends on the rendering software your viewer application or printer uses. To get good results all the time, make each pixel in your image an 8x8 block of pixels of the same color. The blurring then only affects the pixels at the edge of each block. 8x8 blocks are best as they compress without nasty artifacts using DCT compression (sometimes used in eps files).
Old question, but highly ranked in Google, so here is my answer:
Open the .eps-file with a text editor, search for "Interpolate" and change the following "true" to "false". Repeat that step for all Interpolate-statements.
It might also depend on the viewer you're using, but probably just because some viewers ignore the "Interpolate"s...
Had the same problem using plot2svg in Matlab and exporting from Inkscape to eps.