I want to retrieve metadata (width, hight, format ..) from image file (jpeg, png, bmp etc.) in the Html5.
I can use Canvas Api to deal width image.
However, I cannot find Api to retrieve metadata from a file.
Does anyone can know me?
It looks like this little lib might do the trick for you.
Related
I have five compressed images and I need to find raw data from these images. That's why I have to find out the Jpeg heading. but the header of each image is different.I think jpeg doesn't have a fixed header like bmp etc.
JPEG does not define a header or a file format at all. There are several jpeg file formats in use, notably JFIF, EXIF, SPIFF, and Adobe.
The formats define APPn markers that are expected to appear after the SOI marker. However, most decoders will try to figure the image out without these headers.
You do not need a header to find the image data. You scan the stream for JPEG markers.
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
First I'll start with my assumptions about thumbnail:
Thumbnail is the same image reduced by size so it is smaller in size and faster to load
In Exif data there is referance to Thumbnail Image so it might be part of the jpg file
Now what I think is that theoretically I can "inject" to a jpg file another thumbnail so that in windows i will see a small picture and when I will open the file I will see other picture
And my question is in guidlines how do I do that?
Thanks!
Some JPEG file format support including a thumbnail as part of the image header. In the JFIF format, the thumbnail can be either an RGB bitmap or a nested JPEG stream.
You need a JPEG encoder that will insert a thumbnail into the JPEG header. It's that simple. ImageMagic will do it. Many other JPEG encoders will do it as well.
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.
If i am making a image sharing service website using the standard file upload form what images can i say it supports, other then jpg, png, gif. Is there a list that shows what browsers supports what? I know that jpg png and gif are most common but what are the others. I want to be sure.
Honestly, that's pretty much all you should be concerned with. Any other file formats (like svg) are not widely supported enough.
I would suggest converting other types of files to those 3
Examples:
jpeg (simple renaming)
bmp
tiff
pcx