How can read PNG image in actual size?

I have tried to read image using imread but It read image with small size!

[Walter Roberson]

What does imfinfo say the number of rows and columns are? What does size() show after you imread?

[Noor Abbas]

imfinfo says small size as well but the size of image on desk is 68 MB and the size of image as read in computer is 225*171?

[Walter Roberson]

Can you attach the image file?

[Noor Abbas]

I have tried to attached a copy of image but Matlab offer 2MB to attached not 68 MB.

Do you have another way to attached this image?

Thanks in advance

[Walter Roberson]

You can possibly zip it and attach that.

Or you can put it up on google drive or dropbox.

Answer 1

[Image Analyst]

Obviously your screen is not 68 MB in size so you're either going to have to demagnify the image to see all of it, or you're going to have to just look at a small part of it, in its pixel-for-pixel true size, though a small window.

See my attached zoom demo, and also look into the function truesize().

[Walter Roberson]

No, that isn't the problem. imfinfo() and sizeof() are showing that the image is 225*171 which is strange because the file is 68 megabytes . The hypothesis is that there is a larger image in the file.

[Noor Abbas]

yes Walter Roberson,

I have tried to upload image but still not working

[Image Analyst]

He can drop it in his MATLAB online drive (preferably) and give us the link.

Alternatively use Google drive or dropbox or similar.

[Noor Abbas]

Dear Walter Roberson and Image Analyst,

Could you please find link of image , the attached image is 46MB on mylaptop, but when read it in Matlab is 120*160 .

the link is

https://drive.matlab.com/sharing/e4e152c4-ec7a-47b0-88e8-e06a4c7b83ef

Thanks in advance

Answer 2

[Walter Roberson]

That is not a PNG file, it is a DNG file, which is a TIFF variation used to store raw image data.

T = Tiff('L1.DNG');
offset = getTag(T, 'SubIFD');
setSubDirectory(T,offset)
imCFA = read(T);

This will give you Color Filter Array (CFA) data as uint16 -- sort of like Bayer Mosaicing

The imCFA array is 4000 x 5984 . Apple's Preview says the image is 5976 × 3992 after demosaicing.

Unfortunately Tiff class does not know about the tags needed to read the CFAPattern. Apple Preview says it is 2, 1, 1, 0, which would correspond to Blue, Green, Green, Red. Unfortunately I have not yet figured out how to decode the information.

The file includes a 599040 byte "MakerNotes" TIFF tag. https://owl.phy.queensu.ca/~phil/exiftool/idiosyncracies.html says that your particular model of Leica, Leica M (Type 240) has the most idiotic MakerNotes format out of all of the Leica models out of all camera manufacturers. Somewhere in there is a preview image.

[Noor Abbas]

I have same problem with PNG image

[Walter Roberson]

We will need the PNG file to investigate then.

[Noor Abbas]

please find PNG image in the below link

https://drive.matlab.com/sharing/e4e152c4-ec7a-47b0-88e8-e06a4c7b83ef

[Walter Roberson]

I have no difficulty using imread('1.png') in MATLAB ? The file is a bit larger than I would expect, but you do get a full-sized image out. Perhaps there is a preview image somewhere inside the file.

[Walter Roberson]

I am not at all confident as to interpretation, but parts of the file hint that there might be a 1920 x 1280 preview inside the file.

[Noor Abbas]

Thanks Walter Roberson for everything.