I know that the automatic rotation of JPG files is disabled in browsers.

They can not enable it because it would break the layout of some websites.

Is there a CSS property?
or javascript code to achieve that?
or something else?
or maybe the solution to this problem doesn&#39;t exist yet?

Is there a way to tell browsers to honor the jpeg exif orientation?

When uploading a file (jpeg) via a form in IE7 I am seeing a mime-type of &quot;image/pjpeg&quot; instead of &quot;image/jpeg&quot; (as I see in Firefox or similar).  It&#39;s easy enough to work around this problem, but I&#39;m just wondering why IE7 is behaving differently in this case?

Why does IE7 specify a mime-type of image/pjpeg rather than just image/jpeg?

PIL does support JPEG in my system.

Whenever I do an upload, my code is failing with:

    File &quot;PIL/Image.py&quot;, line 375, in _getdecoder
        raise IOError(&quot;decoder %s not available&quot; % decoder_name)
    IOError: decoder jpeg not available

How can I resolve this?

Python Image Library fails with message &quot;decoder JPEG not available&quot; - PIL

I am using Python (2.7) and bindings for OpenCV 2.4.6 on Ubuntu 12.04

I load an image

        image = cv2.imread(&#39;image.jpg&#39;)

I then check the shape of the image array

        print image.shape

I get (480, 640, 3), which I expect for a 640x480 colour image. I then convert the image to grayscale and check the shape again.

        gray_image = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
        print gray_image.shape

I get (480, 640, 1), which I expect for a 640x480 **grayscale** image. I then save the image:

        cv2.imwrite(&#39;gray.jpg&#39;, gray_image)

I am on linux, so I tried looking at the image with gThumb, which shows all the colour channels. When I bring the gray image back into OpenCV the image has three channels again.
I am aware of this flag for reading images:

        CV_LOAD_IMAGE_GRAYSCALE - If set, always convert image to the grayscale one

But this sounds like it is going to bring in the image as a colour image and then convert it. I am porting this project to RaspberryPi so I don&#39;t want unecessary operatioms happening.

EDIT: I have done some timing checks and I have discovered that loading an image using the CV_LOAD_IMAGE_GRAYSCALE flag set results in the image loading twice as fast, irrespective of the image input.

         Using a 3072 x 4608 x 3 image
         0.196774959564 seconds with default loading
         0.0931899547577 seconds with CV_LOAD_IMAGE_GRAYSCALE

**The problem seems to be that OpenCV is creating a 3 channel JPG output whether I have a grayscale image matrix or not!**

What other app can I use to make sure I am getting a single 8 bit channel JPG image out??
(Perhaps gThumb is reporting the channels incorrectly).

If the image is not single channel, why is OpenCV saving my grayscale image to a 3 channel image at disk write?

Thanks in advance.


In OpenCV (Python), why am I getting 3 channel images from a grayscale image?

I have the following:

    ghostscript-fonts-5.50-24
    ImageMagick-6.7.2-1
    ghostscript-9.02-1

Which I use to create a series of JPGs for each page using:

    convert -density 175 -colorspace sRGB test.pdf -resize 50% -quality 95 test.jpg

When I run this on my windows machine all appears to work ok, but on our linux server we get the black background problem.

The resulting JPGs have a black background rendering the image un-readable, what am I missing or is there something I should be doing to correct this?

I&#39;ve been all over google for days but each suggestion doesnt seem to work for me.

Any help is much appreciated, thanks in advance :)

**EDIT**

Just noticed this output when converting one of the PDFs that produces the black background:

    **** Warning: Fonts with Subtype = /TrueType should be embedded.
                 The following fonts were not embedded:
                        Arial
                        Arial,Bold
                        Arial,BoldItalic
    **** This file had errors that were repaired or ignored.
    **** The file was produced by:
    **** &gt;&gt;&gt;&gt; Microsoft&#171; Word 2010 &lt;&lt;&lt;&lt;
    **** Please notify the author of the software that produced this
    **** file that it does not conform to Adobe&#39;s published PDF
    **** specification.

This seems related but as we don&#39;t have control over how the PDFs are produced we need some way of fixing this server side.

Thanks again

ImageMagick PDF to JPGs sometimes results in black background

I&#39;m attempting to use Python to convert a multi-page PDF into a series of JPEGs. I can split the PDF up into individual pages easily enough with available tools, but I haven&#39;t been able to find anything that can covert PDFs to images.

PIL does not work, as it can&#39;t read PDFs. The two options I&#39;ve found are using either GhostScript or ImageMagick through the shell. This is not a viable option for me, since this program needs to be cross-platform, and I can&#39;t be sure either of those programs will be available on the machines it will be installed and used on.

Are there any Python libraries out there that can do this?

Converting a PDF to a series of images with Python

I often use `JPEG` images, and I have noticed that there are two very similar file extensions: `.jpg`, which my mobile&#39;s camera and the _Preview_ application use, and `.jpeg`, with which _Image Capture_ saves the images from scanning with my _Canon MX455_ printer. _LaTeX_ doesn&#39;t seem to distinguish, as I gave it a `.jpeg` with the extension changed to `.jpg` and the result seems to be the same as if it had been a `.jpg` right from the start. I have wondered what the difference between the two is. I have come across [this question](https://stackoverflow.com/questions/419584/what-is-the-difference-between-jpg-jpeg-png-bmp-gif-tiff-i), and will certainly read through it, though at the moment I&#39;m slightly out of time. However, from what I saw giving it a quick look, it seems not to distinguish the two extensions. In fact, it seems the file type&#39;s name is `JPEG` and the file extension is `.jpg`:

&gt;JPEG (or JPG, for the file extension; Joint Photographic Experts Group)

(excerpted from the first answer there). So is there any big difference between the two extensions? And if so, what is it?

JPG vs. JPEG image formats

How can I use the Windows command line to change the extensions of thousands of files to `*****.jpg`?

Changing all files&#39; extensions in a folder with one command on Windows

I want to remove the EXIF information (including thumbnail, metadata, camera info... everything!) from JPEG files, but I don&#39;t want to recompress it, as recompressing the JPEG will degrade the quality, as well as usually increasing the file size.

I&#39;m looking for a Unix/Linux solution, even better if using the command-line. If possible, using ImageMagick (convert tool). If that&#39;s not possible, a small Python, Perl, PHP (or other common language on Linux) script would be ok.


There is a similar question, but [related to .NET][1].


  [1]: https://stackoverflow.com/questions/1813676/how-can-i-write-an-exif-header-without-recompressing-the-jpeg-in-net

How to remove EXIF data without recompressing the JPEG?

I&#39;d like to rotate photos based on their original rotation, as set by the camera in JPEG EXIF image data. The trick is that all this should happen in the browser, using JavaScript and `&lt;canvas&gt;`.

How could JavaScript access JPEG, a local file API object, local `&lt;img&gt;` or remote `&lt;img&gt;`, EXIF data to read the rotation information?

Server-side answers are not OK; I am looking for **a client-side** solution. 


Accessing JPEG EXIF rotation data in JavaScript on the client side

When should certain image file types be used when building websites or interfaces, etc?

What are their points of strength and weakness?

I know that PNG &amp; GIF are lossless, while JPEG is lossy.  
But what is the main difference between PNG &amp; GIF?  
Why should I prefer one over the other?
What is SVG and when should I use it?

If you don&#39;t care about each and every pixel, should you always use JPEG since it&#39;s the &quot;lightest&quot; one?

What are the different usecases of PNG vs. GIF vs. JPEG vs. SVG?

I&#39;m using PIL to convert a transparent PNG image uploaded with Django to a JPG file. The output looks broken.

###Source file

![transparent source file][1]

###Code

    Image.open(object.logo.path).save(&#39;/tmp/output.jpg&#39;, &#39;JPEG&#39;)

or

    Image.open(object.logo.path).convert(&#39;RGB&#39;).save(&#39;/tmp/output.png&#39;)

###Result

Both ways, the resulting image looks like this:

![resulting file][2]

Is there a way to fix this? I&#39;d like to have white background where the transparent background used to be.


----------

# Solution

Thanks to the great answers, I&#39;ve come up with the following function collection:

    import Image
    import numpy as np


    def alpha_to_color(image, color=(255, 255, 255)):
        &quot;&quot;&quot;Set all fully transparent pixels of an RGBA image to the specified color.
        This is a very simple solution that might leave over some ugly edges, due
        to semi-transparent areas. You should use alpha_composite_with color instead.

        Source: http://stackoverflow.com/a/9166671/284318

        Keyword Arguments:
        image -- PIL RGBA Image object
        color -- Tuple r, g, b (default 255, 255, 255)

        &quot;&quot;&quot; 
        x = np.array(image)
        r, g, b, a = np.rollaxis(x, axis=-1)
        r[a == 0] = color[0]
        g[a == 0] = color[1]
        b[a == 0] = color[2] 
        x = np.dstack([r, g, b, a])
        return Image.fromarray(x, &#39;RGBA&#39;)


    def alpha_composite(front, back):
        &quot;&quot;&quot;Alpha composite two RGBA images.

        Source: http://stackoverflow.com/a/9166671/284318

        Keyword Arguments:
        front -- PIL RGBA Image object
        back -- PIL RGBA Image object

        &quot;&quot;&quot;
        front = np.asarray(front)
        back = np.asarray(back)
        result = np.empty(front.shape, dtype=&#39;float&#39;)
        alpha = np.index_exp[:, :, 3:]
        rgb = np.index_exp[:, :, :3]
        falpha = front[alpha] / 255.0
        balpha = back[alpha] / 255.0
        result[alpha] = falpha + balpha * (1 - falpha)
        old_setting = np.seterr(invalid=&#39;ignore&#39;)
        result[rgb] = (front[rgb] * falpha + back[rgb] * balpha * (1 - falpha)) / result[alpha]
        np.seterr(**old_setting)
        result[alpha] *= 255
        np.clip(result, 0, 255)
        # astype(&#39;uint8&#39;) maps np.nan and np.inf to 0
        result = result.astype(&#39;uint8&#39;)
        result = Image.fromarray(result, &#39;RGBA&#39;)
        return result


    def alpha_composite_with_color(image, color=(255, 255, 255)):
        &quot;&quot;&quot;Alpha composite an RGBA image with a single color image of the
        specified color and the same size as the original image.

        Keyword Arguments:
        image -- PIL RGBA Image object
        color -- Tuple r, g, b (default 255, 255, 255)

        &quot;&quot;&quot;
        back = Image.new(&#39;RGBA&#39;, size=image.size, color=color + (255,))
        return alpha_composite(image, back)

    
    def pure_pil_alpha_to_color_v1(image, color=(255, 255, 255)):
        &quot;&quot;&quot;Alpha composite an RGBA Image with a specified color.

        NOTE: This version is much slower than the
        alpha_composite_with_color solution. Use it only if
        numpy is not available.

        Source: http://stackoverflow.com/a/9168169/284318

        Keyword Arguments:
        image -- PIL RGBA Image object
        color -- Tuple r, g, b (default 255, 255, 255)

        &quot;&quot;&quot; 
        def blend_value(back, front, a):
            return (front * a + back * (255 - a)) / 255
        
        def blend_rgba(back, front):
            result = [blend_value(back[i], front[i], front[3]) for i in (0, 1, 2)]
            return tuple(result + [255])
        
        im = image.copy()  # don&#39;t edit the reference directly
        p = im.load()  # load pixel array
        for y in range(im.size[1]):
            for x in range(im.size[0]):
                p[x, y] = blend_rgba(color + (255,), p[x, y])
        
        return im

    def pure_pil_alpha_to_color_v2(image, color=(255, 255, 255)):
        &quot;&quot;&quot;Alpha composite an RGBA Image with a specified color.

        Simpler, faster version than the solutions above.

        Source: http://stackoverflow.com/a/9459208/284318

        Keyword Arguments:
        image -- PIL RGBA Image object
        color -- Tuple r, g, b (default 255, 255, 255)

        &quot;&quot;&quot;
        image.load()  # needed for split()
        background = Image.new(&#39;RGB&#39;, image.size, color)
        background.paste(image, mask=image.split()[3])  # 3 is the alpha channel
        return background


## Performance

The simple non-compositing `alpha_to_color` function is the fastest solution, but leaves behind ugly borders because it does not handle semi transparent areas.

Both the pure PIL and the numpy compositing solutions give great results, but `alpha_composite_with_color` is much faster (8.93 msec) than `pure_pil_alpha_to_color` (79.6 msec). &lt;del&gt;If numpy is available on your system, that&#39;s the way to go.&lt;/del&gt; (Update: The new pure PIL version is the fastest of all mentioned solutions.)

    $ python -m timeit &quot;import Image; from apps.front import utils; i = Image.open(u&#39;logo.png&#39;); i2 = utils.alpha_to_color(i)&quot;
    10 loops, best of 3: 4.67 msec per loop
    $ python -m timeit &quot;import Image; from apps.front import utils; i = Image.open(u&#39;logo.png&#39;); i2 = utils.alpha_composite_with_color(i)&quot;
    10 loops, best of 3: 8.93 msec per loop
    $ python -m timeit &quot;import Image; from apps.front import utils; i = Image.open(u&#39;logo.png&#39;); i2 = utils.pure_pil_alpha_to_color(i)&quot;
    10 loops, best of 3: 79.6 msec per loop
    $ python -m timeit &quot;import Image; from apps.front import utils; i = Image.open(u&#39;logo.png&#39;); i2 = utils.pure_pil_alpha_to_color_v2(i)&quot;
    10 loops, best of 3: 1.1 msec per loop


  [1]: http://i.stack.imgur.com/I2uNe.png
  [2]: http://i.stack.imgur.com/rmlPz.png

Convert RGBA PNG to RGB with PIL

I&#39;m working on a web project that involves a dynamically generated map of the US coloring different states based on a set of data.  

This SVG file gives me a good blank map of the US and is very easy to change the color of each state.  The difficulty is that IE browsers don&#39;t support SVG so in order for me to use the handy syntax the svg offers, I&#39;ll need to convert it to a JPG.  

Ideally, I&#39;d like to do this with only the GD2 library but could also use ImageMagick.  I have absolutely no clue how to do this.  

Any solution that would allow me to dynamically change the colors of states on a map of the US will be considered.  The key is that it is easy to change the colors on the fly and that it is cross browser.  PHP/Apache solutions only, please.

  [1]: http://upload.wikimedia.org/wikipedia/commons/3/32/Blank_US_Map.svg

Convert SVG image to PNG with PHP

I was wondering if PNG contains data like the following?

What I did was to convert the jpg file to png format, and I was expecting to retrieve the same info I had on the jpg as below:

*Currently using this [as3 library][1] to read the data.*

- IDF0--- IDF @[134 - 248] (9 entries)
 - Orientation (SHORT) : 1 	
 - XResolution (RATIONAL) : 72/1 	
 - YResolution (RATIONAL) : 72/1
 - ResolutionUnit (SHORT) : 2 	
 - Software (ASCIIx16) : QuickTime 7.6.6 	
 - DateTime (ASCIIx20)  : 2011:10:02 22:43:37 	
 - HostComputer (ASCIIx16)  : Mac OS X 10.6.8
 - Exif IFD (LONG) : 8  34853	
 - GPS IFD (LONG) : 248

&amp;nbsp;

- EXIF IDF--- IDF @[8 - 134](10 entries)
 - ExifVersion (UNDEFINEDx4) : 0220
 - DateTimeOrigina (ASCIIx20)  : 2011:04:14 17:22:01
 - UserComment (UNDEFINEDx63)  : ASCII
 - FlashpixVersion (UNDEFINEDx4) : 0100
 - ColorSpace (SHORT) : 1
 - PixelXDimension (LONG) : 1022
 - PixelYDimension (LONG) : 486
 - Unknown (ASCIIx13)  : Image Tag-LOL
 - SceneCaptureType (SHORT) : 0

&amp;nbsp;

- GPS IDF--- IDF @[248 - 338](7 entries)
 - Interoperability Index (ASCIIx2) : N
 - Interoperability Version (RATIONALx3)  @425: 52/1, 1144/100, 0/1
 - Unknown (ASCIIx2) : W
 - Unknown (RATIONALx3)  : 1/1, 4392/100, 0/1
 - Unknown (RATIONAL)  : 5/1
 - Unknown (ASCIIx2) : T
 - Unknown (RATIONAL)  : 3694/117

&amp;nbsp;

  [1]: http://code.google.com/p/as3-xmp-file/

Does PNG contain EXIF data like JPG?

Do you know of any tools (preferrably command-line) to automatically and losslessly optimize JPEGs that I could integrate into our build environment? For PNGs I&#39;m currently using [PNGOUT][1], and it generally saves around 40% bandwidth/image size.

At the very least, I would like a tool that can strip metadata from the JPGs - I noticed a strange case where I tried to make thumbnail from a photograph, and couldn&#39;t get it smaller than 34 kB. After investigating more, I found that the EXIF data was still part of the image, and the thumbnail was 3 kB after removing the metadata.

And beyond that - is it possible to further optimize JPGs losslessly? The PNG optimizer tries different compression strategies, random initialization of the Huffmann encoding etc. 

I am aware that most savings come from the JPEG quality parameter, and that it&#39;s a rather subjective measure. I&#39;m only looking for a tool that can be run as a build step and that losslessly squeezes a few bytes from the images.

  [1]: http://www.advsys.net/ken/util/pngout.htm

Tools for JPEG optimization?

Why am I getting the message &quot;Not a JPEG file: starts with 0x89 0x50&quot; when I try to open my jpg file?


Why am I getting the error: &quot;Not a JPEG file: starts with 0x89 0x50&quot;

I have an app that will display a bunch of images in a slideshow.  Those images will be part of the bundle, thus distributed with the app. 

All the images are photographs or photographic, etc.

I&#39;ve read that it&#39;s preferred to use PNG as the image format, but seeing that the JPG version will be much smaller, I&#39;d rather be using that.

Are there any guidelines which format to use and in which case?

When to use PNG or JPG in iPhone development?

I understand that JPEG is a lossy compression standard, and that the &#39;quality&#39; factor controls the degree of compression and thus the amount of data loss.

But when the quality number is set to 100, is the resulting jpeg lossless?

Is JPEG lossless when quality is set to 100?

What&#39;s the most efficient way to resize large images in PHP?

I&#39;m currently using the [GD][1] function imagecopyresampled to take high resolution images, and cleanly resize them down to a size for web viewing (roughly 700 pixels wide by 700 pixels tall).

This works great on small (under 2 MB) photos and the entire resize operation takes less than a second on the server. However, the site will eventually service photographers who may be uploading images up to 10 MB in size (or images up to 5000x4000 pixels in size).

Doing this kind of resize operation with large images tends to increase the memory usage by a very large margin (larger images can spike the memory usage for the script past 80 MB). Is there any way to make this resize operation more efficient? Should I be using an alternate image library such as [ImageMagick][2]?

Right now, the resize code looks something like this

    function makeThumbnail($sourcefile, $endfile, $thumbwidth, $thumbheight, $quality) {
        // Takes the sourcefile (path/to/image.jpg) and makes a thumbnail from it
        // and places it at endfile (path/to/thumb.jpg).

        // Load image and get image size.
        $img = imagecreatefromjpeg($sourcefile);
        $width = imagesx( $img );
        $height = imagesy( $img );

        if ($width &gt; $height) {
            $newwidth = $thumbwidth;
            $divisor = $width / $thumbwidth;
            $newheight = floor( $height / $divisor);
        } else {
            $newheight = $thumbheight;
            $divisor = $height / $thumbheight;
            $newwidth = floor( $width / $divisor );
        }

        // Create a new temporary image.
        $tmpimg = imagecreatetruecolor( $newwidth, $newheight );

        // Copy and resize old image into new image.
        imagecopyresampled( $tmpimg, $img, 0, 0, 0, 0, $newwidth, $newheight, $width, $height );

        // Save thumbnail into a file.
        imagejpeg( $tmpimg, $endfile, $quality);

        // release the memory
        imagedestroy($tmpimg);
        imagedestroy($img);

  [1]: http://en.wikipedia.org/wiki/GD_Graphics_Library
  [2]: http://en.wikipedia.org/wiki/ImageMagick


Efficient JPEG Image Resizing in PHP

This is really a two part question, since I don&#39;t fully understand how these things work just yet:

My situation: I&#39;m writing a web app which lets the user upload an image. My app then resizes to something displayable (eg: 640x480-ish) and saves the file for use later.

My questions:

1. Given an arbitrary JPEG file, is it possible to tell what the quality level is, so that I can use that same quality when saving the resized image?
2. Does this even matter?? Should I be saving all the images at a decent level (eg: 75-80), regardless of the original quality?

I&#39;m not so sure about this because, as I figure it: (let&#39;s take an extreme example), if someone had a 5 megapixel image saved at quality 0, it would be blocky as anything. Reducing the image size to 640x480, the blockiness would be smoothed out and &lt;strike&gt;barely&lt;/strike&gt; less noticeable... until I saved it with quality 0 again...

On the other end of the spectrum, if there was an image which was 800x600 with q=0, resizing to 640x480 isn&#39;t going to change the fact that it looks like utter crap, so saving with q=80 would be redundant.

Am I even close?

*I&#39;m using GD2 library on PHP if that is of any use*

Is it possible to tell the quality level of a JPEG?

As a general rule of thumb when is it appropriate to make a gif interlaced, a png interlaced and a jpeg progressive?

Especially when publishing the image on the web.

When to interlace an image?

How do I execute ImageMagick&#39;s `convert` if I want a JPEG *from the first page only* of a multi-page PDF?


How to execute ImageMagick to convert only the first page of the multipage PDF to JPEG?

I&#39;ve been a web developer for quite some time, and I am used to transforming all my designs into the png file format in order to build my webpages. Despite the fact that png, contrary to jpg, allows transparency in the images, is it a better solution? 

The question regards page loading time and best webdesign practices, as well as file size versus quality of the images.

What do you think is the best solution to use?

webdesign - jpg or png, which one is the best for web

Apple has introduced a new image format in iOS 11 called [HEIF](https://en.wikipedia.org/wiki/High_Efficiency_Image_File_Format) (.heic file extension). I know you can export images as JPG from iOS devices, but I want to upload the HEIC-files to my server and convert them there to JPEG files that can be shown on all other devices.

Can anyone recommend a good and efficient way to achieve this?

&gt; ANSWER:
&gt;
&gt; Since this question has been closed, I will edit in my answer here for the rest of you. We now use this library for converting HEIC to JPEG: https://github.com/monostream/tifig
&gt;
&gt; Also [ImageMagick now support converting HEIC to JPEG](https://github.com/ImageMagick/ImageMagick/issues/507) thanks to [a fork from @toshic](https://github.com/toshic/ImageMagick)
&gt;
&gt; Thank you to [@monostream](https://github.com/monostream) and [@toshic](https://github.com/toshic) for your great contributions!


EDIT1: Edited the wording of the question to be more specific and meet SO guidelines

EDIT2: Added answer since this topic is now closed :/

Convert HEIF (.heic) to JPEG on a server?

I am taking a jpg image and using numpy&#39;s fft2 to create/save a new image. However it throws this error 

    &quot;IOError: cannot write mode F as JPEG&quot; 

Is there an issue with CMYK and JPEG files in PIL???

    p = Image.open(&#39;kibera.jpg&#39;)
    bw_p = p.convert(&#39;L&#39;)
    array_p = numpy.asarray(bw_p)
    fft_p = abs(numpy.fft.rfft2(array_p))
    new_p = Image.fromarray(fft_p)
    new_p.save(&#39;kibera0.jpg&#39;)
    new_p.histogram()


PIL cannot write mode F to jpeg

I&#39;m building an app that uses a lot of images, so it&#39;s getting pretty big. I got more than 15mb in PNG images, and if I convert those images to JPG I would get 5MB or less! So, why should I use PNG instead of JPG?

I know that PNGs are preferred, but what would I lose with JPG?

EDIT: Thank you everybody!

Just a note: Since I got my answer and turns out that I will need to use PNG in most files, I found out that website http://tinypng.org/ , and that&#39;s helping me a lot. My 15mb of images are now 7mb. So, if anyone is in the same situation that I am, I hope that it helps!

Why should I use PNG and not JPG?

I have a bunch of high quality PNG files.  I want to use PHP to convert them to JPG because of it&#39;s smaller file sizes while maintaining quality.  I want to display the JPG files on the web.

Does PHP have functions/libraries to do this?    Is the quality/compression any good?

Use PHP to convert PNG to JPG with compression?

I&#39;ve got a JPEG image which was taken on an iphone. On my desktop PC (Windows Photo Viewer, Google Chrome, etc) the orientation is incorrect.

I&#39;m working on an ASP.NET MVC 3 web application where i need to upload photos (currently using plupload).

I&#39;ve got some server-side code to process images, including reading EXIF data.

I&#39;ve tried reading the `PropertyTagOrientation` field in the EXIF meta data (using GDI - `Image.PropertyItems`), but the field isn&#39;t present.

So it&#39;s either some specific iphone meta data, or some other meta data.

I&#39;ve used another tool like Aurigma Photo Uploader, and it reads the meta data correctly and rotates the image. How does it do this?

Does anyone know what other JPEG meta data could contain the information required in order to know that it needs to be rotated, that is used by Aurigma?

Here&#39;s the code i&#39;m using to read the EXIF data:

    var image = Image.FromStream(fileStream);
    
    foreach (var prop in image.PropertyItems)
    {
       if (prop.Id == 112 || prop.Id == 5029)
       {
          // do my rotate code - e.g &quot;RotateFlip&quot;
          // Never get&#39;s in here - can&#39;t find these properties.
       }
    }

Any ideas?



Problem reading JPEG Metadata (Orientation)

I found JPG does not support transparency, the alpha value is always 255. I am wondering only png supports transparency?

Only PNG supports transparency, is that true?

I am currently working on an application that requires high-performance conversion of an unpadded byte array to either a PNG or JPEG. The image format doesn&#39;t matter, just as long as it&#39;s fast.

I have tried the .NET libraries and the performance is very bad. Can anyone recommend a good freeware library for this?

EDIT: the byte[] is an 8bit grayscale bitmap

Converting a byte array to PNG/JPG

I am trying to convert a Base64String to an image which needs to be saved locally.

At the moment, my code is able to save the image but when I open the saved image, it says &quot;Invalid Image&quot;.

![enter image description here][1]


  [1]: http://i.stack.imgur.com/s6aIa.png

Code:

    try
    {
        using (var imageFile = new StreamWriter(filePath))
        {
            imageFile.Write(resizeImage.Content);
            imageFile.Close();
        }
    }

The `Content` is a `string` object which contains the Base64 String.

C# Base64 String to JPEG Image


I have a BufferedImage I&#39;m trying to write to a jpeg file, but my Java program throws an exception. I&#39;m able to successfully save the same buffer to a gif and png. I&#39;ve tried looking around on Google for solutions, but to no avail.

Code:

	   File outputfile = new File(&quot;tiles/&quot; + row + &quot;:&quot; + col + &quot;.jpg&quot;);
	   try {
		   ImageIO.write(mapBufferTiles[row][col], &quot;jpg&quot;, outputfile);
	   } catch (IOException e) {
		   	outputfile.delete();
	   		throw new RuntimeException(e);
	   }


Exception:


	 Exception in thread &quot;main&quot; java.lang.RuntimeException: javax.imageio.IIOException: Invalid argument to native writeImage
	 at MapServer.initMapBuffer(MapServer.java:90)
	 at MapServer.&lt;init&gt;(MapServer.java:24)
	 at MapServer.main(MapServer.java:118)
	 Caused by: javax.imageio.IIOException: Invalid argument to native writeImage
	 at com.sun.imageio.plugins.jpeg.JPEGImageWriter.writeImage(Native Method)
	 at com.sun.imageio.plugins.jpeg.JPEGImageWriter.writeOnThread(JPEGImageWriter.java:1055)
	 at com.sun.imageio.plugins.jpeg.JPEGImageWriter.write(JPEGImageWriter.java:357)
	 at javax.imageio.ImageWriter.write(ImageWriter.java:615)
	 at javax.imageio.ImageIO.doWrite(ImageIO.java:1602)
	 at javax.imageio.ImageIO.write(ImageIO.java:1526)
	 at MapServer.initMapBuffer(MapServer.java:87)
	 ... 2 more


ImageIO not able to write a JPEG file

I&#39;m using [`javax.imageio.ImageIO`][2] to save a `BufferedImage` as a jpeg file. 
In particular, I created the following Java function:

    public static void getScreenShot(BufferedImage capture, Path folder, String filename) {
            try {
                ImageIO.write(capture, &quot;jpeg&quot;, new File(folder.toString()+&quot;/&quot;+filename+&quot;.jpg&quot;));
            } catch (AWTException | IOException ex) {
                Logger.getLogger(ScreenShotMaker.class.getName()).log(Level.SEVERE, null, ex);
            }
    }

Likewise any image manipulation software, I wish to change the compression level of the jpeg file. However, I&#39;m searching for this option that seems to be missing in `ImageIO`. 

Can I set the compression level and how?


  [1]: http://docs.oracle.com/javase/6/docs/api/java/awt/Robot.html
  [2]: http://docs.oracle.com/javase/6/docs/api/javax/imageio/ImageIO.html

All Jpeg Solutions on Gang of Coders

Total of 33 Jpeg Solutions