Here is the problem to change an image resolution from 300 dpi to 200 dpi or 600 dpi.
i am using matlab but how can i be. so for i have use the imresize function which down sample the image and up sample it.
imresize(image, scale ,interpolation).
how can down sample the image to reduce its quality too. so that i may check the difference between the original image and the down sampled image.
j= imresize(I,0.2,'nearest');
where I is the original image and j is the down sampled image. is this changing the dpi of an image.
Dots per inch (DPI) has nothing to do with the type of resizing done by imresize. In fact, changing the DPI does not even require changing the actual image data, just the metadata -- a property or label. DPI gives you the information needed to go from pixels -> inches (print size).
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I'm trying to create MATLAB figures to put into a paper. The paper has very specific sizing instructions for figures that I'm having trouble matching in MATLAB. The figures need to be no greater than 3.5" width, >300 DPI, with 8pt font.
In my code, I use the following to try to set the parameters:
set(gcf,'PaperUnits','inches');
set(gcf,'PaperPosition',[0 0 3.5 3.5]);
xlabel('x-axis label','FontSize',8);ylabel('y-axis label','FontSize',8);
set(gca,'FontSize',8);
print('-djpeg','-r300','filename.jpg')
This should be giving me a 300 DPI, 3.5"x3.5" JPEG image with an 8pt font size. However, when I import the image into Word, it becomes 6.5" x 6.5" and the font size is larger than Word's 8pt font. Even if I resize the image, the font size is still too large, though it should maintain the same DPI. Are the FontSize and PaperPosition parameters not working as I expect they should or is Word doing something strange for importing?
The font size issue was caused due to differing fonts used in MATLAB and Word. Once I learned about set(gca,'FontName'), the font size seemed to be correct when the image was manually resized to 3.5" x 3.5".
The image size issue seemed to be related to saving it as a JPEG. Once I swapped to PNG, the image was the correct size by default. Looking into the JPEG properties, it had the correct number of pixels for a DPI of 300 at 3.5", the sole issue was that it would have to be manually resized. Thanks for the comments that led me to finding a solution.
I have to resize image i.e if its dimension is 3456x5184 to 700X700 as my code needs image with less number of pixels otherwise it takes too much time to give results.So, when I use imresize command it changes the dimensions of image but at the same time it changes the shape of image i.e the circle in image which I also need to detect looks like oval instead of being cirle. I need your suggestions to resolve this problem. I am really grateful to you people.
Resizing images is done by either subsampling (to get smaller images) or some kind of interpolation (to get larger images)
Input is either a factor or a final dimension for width and height.
The only way to fit a rectangle into a square by simply resizing it is to use different scales for width and height. Which of course will yield in a distorted image.
To achieve what you want you can either crop a 700x700 region from your image or resize image using the same factor for with and height. Then you can fit the larger dimension into 700 and fill the rest around the other dimension with black or whatever you prefer.
I have an gray scale image of size <2559x3105 uint16>. when I try to open this image, I get warning that it is too big. I have tried imresize() function to make it small<512x512 uint8> in size. When I plot the original image and re-sized image, the intensity gets decreased after re-sizing. I want to re-size original image without changing in its pixel values. Is there any solution?
If you would like to keep your final image as uint8, I think you would be needed to first convert the uint16 image to uint8 image using im2uint8 -
uint8_image = im2uint8(uint16_image);
Then you may apply imresize on uint8_image.
But, if you don't want your final image to be of uint8 type, you can directly use imresize and it would keep the datatype, i.e. the resized image would be of uint16 type.
Read the docs and use the nearest neighbor method. That is,
resized = imresize(original, scale, 'nearest')
This will not use interpolated values. The downside is of course that edges might be jagged.
It sounds like your 16-bit image uses linear codes while the resulting 8-bit image needs to be gamma corrected. If this is the case you can use imadjust with a gamma parameter of 1/2.2 to produce the brighter image.
Do you get the warning when you display it with imshow? Does it say something like "Image to large to fit the screen, resizing to xx%"? If so, then you can simply ignore the warning. Otherwise, you can can set the 'InitialMagnification' parameter of imshow to resize the figure, but not the image itself.
This appears to be a trivial problem but the result is strange, totally lost where I am going wrong. There is an input RGB image which needs to be converted to gray scale and sized to 1000 x 1000 pixels. This is how I have done
img=imread('flowers.jpg');
flowers_gray=rgb2gray(img);
flowers_resize=imresize(flowers_gray,[1000 1000]);
but strangely the output image is not of 1000 by 1000 pixels. Moreover, matlab did not save the image (tried using SaveAs option and the File --->Export Setup) gray scale mode
and also the size was incorrect since when I opened the saved image by
img1=imread('flowers_resize.jpg')
s=size(img1)
it gave
s=586 665 3
And the image flowers_resize.jpg is saved with a white border surrounding it in the image folder. So, I went to Paint toolbox to select the image A1 and manually deleted the surrounding background and resized the image.But alas, it saved the image with 3 color channels and not in gray scale mode although the size was correct! Can somebody please point out the correct way of resizing to 1000 by 1000 pixels and saving in gray scale mode without the white border surrounding the saved output file? Thank you.
When you use the image export processing, you are saving the entire figure including the space around the figure (white space).
Instead, use the imwrite command. In your case:
imwrite(A1,'flowers_resize.jpg','jpg');
I created a 8.5x11.0 inches image # a 300dpi setting in photoshop.
When i go to use this as a background image in report designer the image looks hugeee.
It's not fitting within the 8.5x11.0 page.
Is there a way to resize this image correctly so that it will fit correctly within a 8.5x11.0 letter size page?
Thanks in advance,
with the information you gave, i believe your problem is problably in the group Size/dpi
You saved an image of size 8,5 x 11 inches # 300 Dpi (dots per inch) that calculates to aproximately an image of 2550 x 3300 pixels.
Now if your "report designer" software looks only at the size in pixels and assumes a dpi value diferent then the one you used, say for example 72 dpi, your 2550 x 3300 pixels image would actually be something like 45,8 x 35.4 inches.
So, my advice is, find out what are the characteristics your solftware is especting, aparently it is not 300dpi.
If you can´t find the information, try commonly used dpis like 72dpi or 150dpi.