| | <<<Back 1 day (to 2017/02/08) | 20170209 |
| brotherBox | hi guys | 08:59.28 |
| | i have a question that you may or may not help me with | 08:59.46 |
| | essentially i'm asking about details how ghostscript determines their dct table values | 09:00.25 |
| kens | And what do you mean by a 'dot table' ? | 09:00.39 |
| | Sorry dct table | 09:00.58 |
| | I'm assuming this is JPEG related ? | 09:01.04 |
| brotherBox | the distinct cosine table in jpg | 09:01.09 |
| | yes | 09:01.11 |
| kens | We use OpenJPEG | 09:01.17 |
| | And Jpeglib I htink | 09:01.29 |
| brotherBox | *discrete | 09:01.38 |
| kens | I seem to recall (from the last time I implemented a JPEG decoder) that the information is all in the specification | 09:02.08 |
| brotherBox | im essentially trying to find out if the dct of an image was changed and they use artifex software from 2011 | 09:02.11 |
| | they do some pdf and ghostscript processing shizzle | 09:02.26 |
| kens | OK so we're talking JPEG encoding not decoding | 09:02.34 |
| | I doubt if you can tell whether they used Ghostscript by looking at the DCT. If its a PDF file that's been produced we can probably tell if that used Ghostscript | 09:03.08 |
| brotherBox | its from a pdf that got converted into a jpg | 09:04.26 |
| kens | Rendered by Ghostscript ? I doubt you can tell that. | 09:04.49 |
| | IIRC the DCT values are modified by the QuantTables and QFactor (if supplied) | 09:05.10 |
| | Well, if its a recent jpeg produced by a recent version of Ghostscript, it will have an embedded ICC profile, which will tell you if it was produced by GS. | 09:12.11 |
| | Apart from that I think (looking at the code) you are out of luck, I don't believe there's any way to tell from the DCT tables in a JPEG if it was produced by Ghostscript | 09:12.45 |
| | We use the IJG JPEG code, so I don't think you coudl tell a default version of our JPG from any othere implenentation using the IJG code (which is very widespread). ANd as I said, the device takes parameters which I think will modify those tables anyway, so if those were used, you again would find it hard to tell if a given JPEG was produced by GS | 09:15.19 |
| | Why do you want to know anyway ? | 09:17.09 |
| onecool | looking for stego :) | 09:18.04 |
| kens | Ah, NSA spook :-) | 09:18.32 |
| onecool | no it's for cicada 3301 lol | 09:18.49 |
| | help is welcomed | 09:19.05 |
| brotherBox | not really NSA | 09:19.44 |
| | cicada is an online puzzle | 09:19.50 |
| kens | Yeah I know what cicada is | 09:20.01 |
| brotherBox | and we're trying to find something out because we're kind of stuck | 09:20.13 |
| | "kind of" => massively stuck | 09:20.41 |
| kens | I doubt I can help, too busy to mess with puzzles like that. | 09:20.45 |
| | I suspect you;d do better on #cicadian | 09:21.14 |
| onecool | hah | 09:21.18 |
| brotherBox | lol | 09:21.25 |
| | that channel died because i killed it | 09:21.33 |
| onecool | we're busy too :) | 09:21.41 |
| | you're not cicada are you | 09:21.44 |
| kens | Well I don't try to keep up with that stuff | 09:21.49 |
| brotherBox | he may be | 09:21.51 |
| onecool | they used your tools, so we figured we'd ask | 09:24.31 |
| | ty for answering | 09:24.35 |
| kens | SOrry, GS is open source, anyone can use it :-) | 09:24.45 |
| brotherBox | what onecool said | 09:24.52 |
| | sorry if we annoyed you, we appreciate your help | 09:25.01 |
| kens | Not a problem | 09:25.09 |
| Wapsi | Hi, is it possible to use GSView just for printing? Like: gsview.exe -print "printer name" foobar.pdf - and then it just prints the document and quits | 09:39.17 |
| kens | Which version of GSView ? | 09:39.31 |
| Wapsi | gsview_setup_6.0.exe from here: http://www.gsview.com/downloads.html | 09:40.13 |
| kens | THen I believe, currently, the answer is 'no'. I think its on the roadmap, possibly as a separate binary. | 09:40.40 |
| Wapsi | I didn't find any command line help/manual from their web page or application help | 09:40.45 |
| | Ok. | 09:40.54 |
| | Forward 1 day (to 2017/02/10)>>> | |
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