On OSX I converted a multi-page PDF file to PNG and (somehow) it created a multi-page PNG file.
Is there an extension to the PNG format that allows this? Or is this not something I can validly create?
~~~~
To clarify, this is a PNG file, per the builtin file command and the identify command from imagemagick.
$ file algorithms-combined-print.png
algorithms-combined-print.png: PNG image data, 1275 x 1650, 8-bit/color RGBA, non-interlaced
$ identify algorithms-combined-print.png
algorithms-combined-print.png PNG 1275x1650 1275x1650+0+0 8-bit sRGB 3.537MB 0.000u 0:00.000
And here is a pastebin of the command identify -verbose algorithms-combined-print.png: http://pastebin.com/hw1yuRKa
What is notable from that output is that the pixel count is Number pixels: 2.104M which corresponds to one page. However, the file size is 3.537MB, which is clearly sufficient to hold all the pages.
Per request, here is the output of pngcheck: http://pastebin.com/aCRMEd9L
PNG does not support "multipage" images.
MNG is a PNG variant that supports multiple images - mostly for animations, but it's not a real PNG image (diffent signature/header), and has never become popular.
APNG is a similar attempt, but more focused on animations - it's more popular and alive, though it's less official - it's also PNG compatible (a standard PNG viewer, unaware of APNG, will display it as a single PNG image).
Another possible explanation is that your image is actually a TIFF image with a wrong .png extension, and the viewer ignores it.
The only way to know for sure is to look inside the image file itself (at least to the first bytes)
Update: given the pngcheck output, it seems to be a APNG file.
Related
I have a PDF file which is made of photographs of a book connected in a single PDF file. I'm trying to convert it back to single images in PNG format, every tool I tried asks me to set DPI which alters the size of resulting images, is there a way to get images of the exact same pixel size the original images were?
Most PDFs of books contain a single image per page and depending on the scanner these images can basically be in three different formats: JPEG, JPEG2000 or TIFF. JPEG2000 is rarely used, so your PDF probably contains JPEG and/or TIFF images.
The good thing about JPEG (and JPEG2000) images is that they can be embedded as-is into a PDF! So you can extract the images as they are stored in the PDF. With TIFF this is also sometimes possible (but I don't think always...).
As mentioned by Tim Roberts you should try using pdfimages or hexapdf images to view and extract the images stored in the PDF. This will give you the best result.
As we all know that jpg image format does not support transparency.
so we use .png format.
i was surfing on net and i found an image with .jpg format and
transparent. it is wonder how a jpg format image can be transparent.
here is the example image.
http://bdthemes.net/demo/joomla/intensy/images/sampledata/features/top_b.jpg
The provided example image is in fact not a JPEG, but a png file.
It has the extension and mime-type of a jpeg file, but it's contents are in png format.
JPEG file format does not support transparacy.
So if you need transparancy in images for use in browsers.
You can either:
convert the image to png, this works in all browsers
use ZorroSVG, requires SVG support but results in smaller files for photographic images.
use webp, only use when you have fallbacks in place for browsers that do not support webp.
The new JPEG-XR standard supports transparency.
However, this is not a real JPG, it's a PNG. If you rename it to .txt, you can see that the contents of the file start with PNG:
check its mime type, it must be renamed .png to .jpg
I have a weird problem in matlab. I have code that takes in a directory of jp2 files and converts all of them to either tiff, png, or a jpg file. Then it puts these files in a new directory. The user can specify how big they want the file to be in terms of how many pixels are used (EX: 1:3:end is every three pixels). This code works perfectly for the png and tiff conversions.
With the jpg conversion there is no error whatsoever but when I go to click on the jpeg file in the new folder (which it does go to at least) It says "Windows Photo Viewer can't open this picture because the file appears to be damaged, corrupted, or is too large" I tried opening the pictures in other viewers but it said the same thing. All of the png and tiff pictures opened fine.
Some help would be greatly appreciated, thanks!
Edit: I noticed when I call imshow on the location of the jpeg file it actually does show up in matlab. It still does not show up in any image viewers though
IPA image uses pngcrush to compress PNG image, but I want to uncrush a PNG image on Ubuntu.
Can anyone give me any idea?
The standard PNG utility pngcrush has been modified by Apple, which makes it produce technically invalid PNGs: a new chunk is inserted before the mandatory first chunk IHDR, RGB(A) order of pixel data is inverted, and RGB pixels get premultiplied with their alpha.
Hence, I'd rather call these PNGs "fried", rather than just "crushed".
Try my own pngdefry. The source code is written on a Mac OSX machine but it should be compilable for other OSes as well; it's pretty straightforward C code.
Need to convert pdf file to image file (jpg, png, gif) to show on the web.
Exploring goole application to that reads PDF files shows that they are using PNG. But hov to onvert 2000x2000 file so it have only 150 kb?
Is there any command line tool?
PNG and GIF are better than JPEG, GIF probably better than PNG. TIFF usually is the best.