I want to make a steganographic image using some very simple software. I want to demonstrate the principle by opening up a bitmap image file in an editor that will let me see the binary that encodes the colours of individual pixels. I want to change the last couple of bits for some pixels to hide my secret binary message, then re-save the image. I have seen that there are a few applications available that can create steganographic images, some of which are free, but they seem to hide what is really going on. I want to see and edit the 'raw' binary for myself. I hoped something like Notepad++ or Cyberchef would let me do this, but apparently not. Can you suggest something I can use please?
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So, I don't believe that exists someway to "read" a PNG through its binary code, or something like that, but I have zero knowledge on Image Processing or Computer Vision, and so, I can't be sure if that are ways to do it or not.
To be clear: I want to know if there are ways to identify the image of a Logo using an image of the Logo as reference but through methods that use only the binary of the image.
Thanks in advance
If the logo is known, and not distorted a lot (logo printed on a scarf is not as good as on a flat surface), there is technologies that can achieve that:
It is a template matching problem, see https://docs.opencv.org/4.5.2/d4/dc6/tutorial_py_template_matching.html.
I'm making a poster (sort of) and would like to do these things, but I'm not sure if AsciiDoc or AsciiDoctor can do them, and if so, how:
Background image that can be stretched to the poster's dimensions
A rectangle with some transparency and a border, basically a bright frame, with text in it.
An image with text in it.
Text inside an image inside a rectangle.
(Bonus question: Is it possible to free-form specify where something goes, e.g. x=80%, y = 20% for something in the top right corner?)
I'm not sure that it makes sense to use AsciiDoc to source poster output, as opposed to a desktop publishing tool or a graphics program.
But if you are converting to HTML, you should be able to accomplish most of this with clever sourcing and some CSS/JavaScript on the front end. That is, you can source some of the metadata you want to impose on the final image, then have front-end code do the manipulation and imposition. For instance, you can provide a caption, classes, a title, and other info in the source, but AsciiDoc is intentionally agnostic about how that stuff is handled in output.
However, unless you need to create these things as part of technical documents, especially ones getting built/generated recuringly with automation, you're likely better off with a specialized tool.
This may sound like stupid question, but for me it's important.
I don't have much experience with using Photoshop, because Inkscape is perfect for my needs (web). Now I would need to create something and print it. I know that color mode for printing should be CMYK.
Because I am more familiar with Inkscape(that does not support CMYK), can I create PDF in that program and then import it into Photoshop and change color mode to CMYK. Is that valid? It shows that color mode is changed, but is that all? Because this is not for me and I just want to know if person that I wouk this for will not have any problems when it comes to printing. How can I make sure that conversion to CMYK was good?
One more question. In Inkscape I can not crop image, but I can mask or clip it. Basically, image still exist, but you see only portion of it. When it comes to printing will printer print full image or just that portion of it or I will need to crop image?
For most part, when you print an RGB file on your printer, the printer will convert it to CMYK. It's ability to do so "well" will depend on how accurate you need it to be & what color profile it is printing from (sRGB generally turns out better than say AdobeRGB).
The main reason for you to convert a file is so that you can make any fine tune adjustments to the image after the change. So you're not leaving it to the printer to decide and possibly mess up.
I'm not familiar with InkScape so don't know how it'll export said artwork. When you open it in Photoshop however, you will be able to see if it tacked it on there. Then you can crop if need be.
Hope that helps.
I have a set of really big images out of which I need to crop little snippets. These snippets are all exactly the same size but don't follow a strict pattern so I can't do this programatically.
Ideally I would like to open up one of the big files and be able to point and click on say, the top left corner of a snippet and have that automatically be saved to disk without even having to enter a file name, and then continue on with the rest. (Of course this would be the ideal way which I know is probably way off the real possible way!).
I started doing this in Photoshop CS4 but cropping a snippet, saving, undoing (to get to the full image), and starting over again takes way too long.
Maybe someone has a better way to do this in photoshop or in some other software.
Thanks for reading!
Instead of cropping and undoing, you could:
make (or resize) a selection
copy the selection to a new image
save the image
close the image
You might need to split it into two actions, I don't know enough about programming Photoshop.
Thank you everyone for your input.
I ended up doing this with a suggestion a colleague of mine came up with. It consisted of creating a Photoshop "slice" over the first region I wanted to crop and then cloning that region over the rest of the other sections. After that, using Save For Web (and ofter hitting Continue when PS complained about how that image was way beyond Save For Web's capabilities) I could save all images at once.
This was the fastest and easiest method I could find. Until then I was going with Mark Ransom's method.
We would like to display very large (50mb plus) images in Internet Explorer. We would like to avoid compression as compression algorithms are not what CSI would have us believe that they are and the resulting files are too lossy.
As a result, we have come up with two options: Silverlight Deep Zoom or a Flash based solution (such as Zoomify). The issue is that both of these require conversion to a tiled output and/or conversion to a specific file type (Zoomify supports a single proprietary file type, PFF).
What we are wondering is if a solution exists which will allow us to view the image without a conversion before hand.
PS: I know that you can write an application to tile the images (as needed or after the load process) and output them; however, we would like to do this without chopping up the file.
The tiled approach really is the right way to do it.
Your users don't want to download a 50mb file before they can start viewing the image. You don't want to spend the bandwidth to serve 50 megs to every user who might only view a fraction of your image.
If you serve the whole file, users will eventually be able to load and view it, but it won't run smoothly for most of them.
There is no simple non-tiled way to serve just a portion of an image unless you want to use a server-side library like imagemagik or PIL to extract a specific subset of the image for each user. You probably don't want to do that because it will place a significant load on your server.
Alternatively, you might use something like google's map tool to provide zooming and scaling. Some comments on doing that are available here:
http://webtide.wordpress.com/2008/08/27/custom-google-maps/
Take a look at OpenSeadragon. To make a image can work with OpenSeadragon, you should generate a zoomable image format which mentioned here. Then follow starting guide here
The browser isn't going to smoothly load a 50 meg file; if you don't chop it up, there's no reasonable way to make it not lag.
If you dont want to tile, you could have the server open the file and render a screen sized view of the image for display in the browser at the particular zoom resolution requested. This way you arent sending 50 meg files across the line when someone only wants to get an overview of the image. That is, the browser requests a set of coordinates and an output size in pixels, the server opens the larger image and creates a smaller image that fits the desired view, and sends that back to the web browser.
As far as compression, you say its too lossy, but if thats what you are seeing you are probably using the wrong compression algorithm or setting for the type of image you have. The jpg format has quality settings to control lossiness, and PNG compression is lossless (the pixels you get after decompressing are the exact values you had prior to compression). So consider changing what you are using as compression, and dont just rely on the default settings in an image editor.