I am trying to decode animated gif89a file. I got &h21 followed by &hc8 In the specs &h21 followed by &hff , or &hfe or &hf9 or &h01 are described. what is extension label &hc8 ?
I umderstand that c8 fallS in the range of labels reserved for comtrol blocks So it cannot be skipped
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I am looking for a way in which it is possible to extract the left side of the image (the non ascii characters) here, reliably, using OCR. I have a number of images in a similar format, also showing hex data, that i would like to extract.
Would anyone be able to reccomend a way to extract the text from these images?
Ideally, the output for first line would be :
0005C850 00 00 00 00 etc.
and output for fourth line would be something like:
0005C8AA ED 93 A7 8E etc.
A legendary program has been written that does this. - https://github.com/eighttails/ProgramListOCR . For Windows systems, i ran on a VM.
Was hard to find.
First you want to convert your image to 400% of the size:
convert -resize 400% source.png source.png
Make it grayscale:
convert source.png -colorspace Gray destination.png
Change it into a tiff file:
convert destination.png destination.tiff
You then process it using this software.
I have jpg file, i can decode it to hex so it is possible to read the inside of file. I have a question, there is any possibility that between SOI and EOI markers there is another image format image hidden ?? The whole file size is around 950kb. I checked for more SOI EOI markers of jpg and i didn't find others so i think i can exclude the possibility of another jpg file inside.
So about other formats it is possible that jpg contains one and how i can check if there is one and even retrieve it ??
I were using this website for analysis after i found that this file is JFIF.
https://en.wikipedia.org/wiki/JPEG_File_Interchange_Format
The whole header is below, as you can see it starts from SOI, then informations about jfif are specified. The thumbnail image pixel size is 0x0 in this header.
FF D8 FF E0 00 10 4A 46 49 46 00 01 01 00 00 01 00 01 00 00
it ends with
FF D9
There could easily be a thumbnail in an APPn marker. Take a look at the JFIF specification, for example.
Such an image would have to be relatively small because APP and COM markers are limited to 64K.
I have read most of the questions here, here,bug and others.
One difference is that all the posts talks about the external image being read.
However i am creating the jpg image from ImageIO library itself and i am writing that image to a file and reading the same image file however there is difference in pixel value.
here's my code:
BufferedImage j = new BufferedImage(100,100,BufferedImage.TYPE_INT_RGB);
Graphics2D jg = j.createGraphics();
jg.setColor(Color.GREEN);
jg.fillRect(0, 0, 100, 100);
jg.dispose();
File gr = new File("d:/pics/green.jpeg");
ImageIO.write(j,"jpeg",gr);
BufferedImage grbr = ImageIO.read(gr);
System.out.format("expected:%s\tactual::%s\n", j.getRGB(40,40), grbr.getRGB(40,40));
System.out.format("expectedG:%s\tactualG::%s", Color.GREEN.getRGB(), grbr.getRGB(40,40));
Output:
expected:-16711936 actual::-16711935
expectedG:-16711936 actualG::-16711935
I read this excerpt from the questions i saw for help as below
All other image loaders assume that the data is YCbCr in that case,
except for ImageIO, which assumes that it is RGB when channels 1 and 2
are not subsampled. So, check whether the first 4 bytes are FF D8 FF
E1, and if so, whether channels 1 and 2 are subsampled
I read the first few bytes of the green.jpeg after it is written to the file like this as below
FF D8 FF E0 00 10 4A 46 49 46 00
I read about JFIF on wikipedia and found that above sequence is not according to what is mentioned as here. However this is not applicable here because i created a simple RGB type image and not YCbCr type.
So why simple image creating and reading in ImageIO is giving different results? Thanks in advance.
The gamuts of the RGB and YCbCr colorspaces are different. That's your first change of having changes. There are various steps in the JPEG process that can introduce rounding errors. The quantization process in JPEG changes values.
You're comparison shows very slight changes that are normal with JPEG.
I have created a image validation system which checks the magic number of an image and tries to validate the image. Digging up google I got the magic number for cursor images from here.
00 00 01 00 // .ico format
00 00 02 00 // .cur format
I have visited many sites which converts images to .cur images, however they're converting it to ico images not cur images :
2.2.1 :012 > File.open('~/Pictures/sample/Sora-Meliae-Matrilineare-Mimes-image-x-ico.ico', 'rb').read(9)
=> "\x00\x00\x01\x00\t\x00\x00\x00\x00"
2.2.1 :013 > File.open('~/Downloads/test.cur', 'rb').read(9)
=> "\x00\x00\x01\x00\x01\x00\x00\x00\x00"
The magic number for ico images is \x00\x00\x01\x00 and for cur images it's \x00\x00\x02\x00.
I have even tried convert command to obtain a cur image but it also results in an ico image:
convert sample.cur test.cur
So how can I get an authentic cur image for testing whose magic no. is \x00\x00\x02\x00? For code reference I have written this blog. Thanks for your help.
I am having a bit of trouble getting Gravatars to work properly:
When I request the following:
http://gravatar.com/avatar/8a17d0d0d8bdf6a8d527bbc943a17cf8.jpg?s=64&d=identicon
Firefox proudly displays the following:
http://files.quickmediasolutions.com/gravatar_p.png
...indicating that the file is a PNG image.
This confuses me - I thought Gravatars were JPEG images. It seems like they can be either. How can I find out if a given image is PNG or JPEG preferably without downloading it first?
Note: Some people are reporting that Gravatar only returns PNG images. Please explain this:
http://files.quickmediasolutions.com/gravatar_p2.png
http://gravatar.com/avatar/03cd042b82ac85b2c5fe0757a94e0413?s=64&d=identicon
If Gravatar icons have accurate MIME types assigned by the server you're accessing them from, just check that. It should be image/jpeg for JPEGs and image/png for PNGs.
Failing that...
http://en.wikipedia.org/wiki/Portable_Network_Graphics#File_header
A PNG file starts with an 8-byte signature. The hexadecimal byte values are 89 50 4E 47 0D 0A 1A 0A; the decimal values are 137 80 78 71 13 10 26 10.
So just check the eight bytes at the beginning of the file; if it's a PNG, it'll have the stated values in those bytes, and if not, it won't. Just download the file, possibly store it somewhere temporarily (which shouldn't be too hard considering it shouldn't be too big), and process it differently depending on what the header contains. You can always change the file extension and then use PHP's graphics library if you saved it as the wrong type at first. (Or are you not allowed to do that?)
As a side note, my favorite bit about the PNG header:
50 4E 47 In ASCII, the letters PNG, allowing a person to identify the format easily if it is viewed in a text editor.
The end tag is JPG, but the string is interpreted by the server and the corresponding image is sent. In this case a PNG.