Nearly all colour laser printers leave a pattern of tiny yellow dots all over the paper. These dots contain information about the printer and perhaps also about the time and date of the print, the IP of your computer and who knows what else. These codes are in there for at least a decade and the EFF has complained in vain. Reality Winner got cought with these dots – but perhaps they would have found out about her a bit later without them.
The EFF has a dorky video about that.
I have a laser printer in my office at school. What does it tell about me? I research that with help of GIMP 2.9 – which looks terrific and has a lot of nice new stuff on board.
And of course you get to see some of these new features.
The companion file contains the scan of the Ordnungsmaßnahmenverordung in different resolutions and the XCF file with the revealed code. The last paragraph on the page gives me the right to take away your phone and hand it back to your parents after a reasonable time – if it beeps again in my class. (A lot of kids would prefer the cane over this…. 😉 )
I forgot about the serial number of the printer – this will be updated soon.
00:00:50 Leaking from the NSA
00:01:35 Little yellow dots on laser print
00:03:00 Gimp 2.9 fired up
00:03:30 Search for the yellow dots
00:04:20 Colour Channels
00:06:00 Extract a colour component
00:06:40 Split view – new in filter dialogs
00:07:15 Searching for the pattern
00:07:55 New things in the layer dialog
00:08:30 Searching for the pattern
00:10:10 Crop tool
00:10:30 Measuring the pattern
00:11:35 Adding a precise grid
00:12:45 30 bytes of data in the yellow dots!
00:14:00 What’s not in the code?
00:15:00 Printing leaves traces
00:16:25 Blunder of “The Intercept”
00:17:00 Anonymising a scan with the threshold tool
00:18:30 The mono mixer for getting red back in
00:20:00 Return of the Minox for leakers?
00:21:00 We need a guide about OPSEC!
00:21:44 End of video
G’MIC is a lot of things that do stuff with images. You have a stand alone program with a complete image manipulation and analysis programming language, an online service and a GIMP plugin that gives easy access to (nearly) the whole package. Don’t get G’MIC from other sources than their pages – the update cycle is so fast that package maintainers can’t keep up. The version recorded in the video is already outdated twice at the time of the publication.
The second part of the video is a promotion for Ramón Miranda‘s very good training DVD “Muses”. It goes through the whole process of learning Krita – a graphics program under Linux and Windows, which is much better for painters than GIMP – up to finishing a real digital painting. You can buy the DVD at the Krita shop, 32.50€ is comparable to other kinds of such DVDs and the proceeds support the Krita Foundation.
I got this one for free – and I will give it away! If you want to have it, write a comment to this blog post before Episode 200 is published. Get your mail address right (it will only be visible to me) and mention that you want the DVD. After the deadline I’ll have some supposedly innocent children draw a winner.
00:00:00 Start of video
00:01:10 Installing the G’MIC Plugin for GIMP
00:03:00 Installing and using G’MIC as a stand alone program
00:10:00 G’MIC Online service
00:10:40 Using the G’MIC GIMP Plugin
00:13:40 Pencil Drawing emulation as an example
00:18:10 Film emulations and grain as an example
00:25:15 Spectral filters – Fourrier included
00:26:20 Plotting Graphs with G’MIC
00:29:20 Ramon Miranda’s Krita tutorial DVD
I went to the Libre Graphics Meeting 2014 in Leipzig to get either a boost for my motivation or to find an end for this project. It turned out to be a booster.
It was a really good time – even with missing the first day and the (for me) most interesting talks because I had to work that day. Another day was spent at the Zoo with Pat David and his wife, more time in the coffee room, Milchbars and restaurants. All the time having good conversations and learning a lot.
And then I got the honors of shooting the traditional group image. I assume it was not my track record of famous group pictures but the 36 megapixel resolution of my D800 that led to that decision.
In this episode I cover the post processing of the image and how I blended my previously taken image into the group.
00:01:14 The LGM Group Photo
00:04:05 Rotating the image
00:06:05 Adjusting contrast and brightness with the curves tool
00:09:23 Getting myself into the image
00:10:54 Registering the layers
00:14:38 Merging with a layer mask
00:17:55 Ways to change the brush size
00:18:50 Cleaning up the layer mask
00:20:38 Curves adjustments on a selection
00:24:28 Cropping the image
00:25:58 Sampling a fill colour out of the image
00:27:14 Sharpening with wavelets
00:31:12 Adding the SVG logo
00:34:04 Scaling down and exporting
00:36:38 Good bye!
The image in this post has been altered a bit more with the GIMP filter “Old Photo” under /Filters/Decor/Old Photo.
00:02:04 Opening an image from the Web
00:03:02 Loading an image from disk and some mistakes to avoid when making your image
00:03:55 Getting an image into another one
00:04:30 Measure Tool
00:05:00 Scaling to the proper size
00:05:25 Copy and Paste between images
00:06:10 RGB- and Grayscale Mode
00:06:30 Save the image in XCF format!
00:07:54 Isolate the person from the background with a layer mask, the Free Hand Selection and a brush
00:10:10 Free Hand Selection
00:12:15 Tedious paint work
00:17:30 “Optimizing” the mask with the curves tool and a blur
00:19:30 Finding the right position and scaling a layer
00:22:15 Adding the Curves Tool to the Toolbox
00:23:20 The Curves Tool
00:26:30 Adding grit and grain by extracting the grain from the image
00:30:00 Bucket fill tool
00:31:08 Try stuff with a layer copy
00:33:06 Adding light and shadows
00:40:20 Move a stack of layers, keeping them aligned
00:41:10 Saving and exporting the image
Grassmann’s Law gives a clue how to create a color sensation in the brain by mixing up some wavelengths out of the spectrum. The CIE finally defines what is visible for a “Standard Observer” and Microsoft & HP (sRGB) and Adobe (Adobe RGB) build their color spaces on that foundation.
00:00:15 Submit to GIMP Magazine
00:00:50 Light as part of the electromagnetic spectrum
00:01:43 Biology of color vision
00:06:14 World Champion of Color Vision: The Mantis Shrimp!
00:06:40 Grassmann’s Law – mixing colors from spectral primes
00:07:22 CIE 1931 Color Space – the standard observer
00:09:00 Elle Stone’s blog – a lot about color!
00:11:40 D65 – the White Point for sRGB
00:11:56 Black Body Radiation and White Points
00:13:44 Bruce Lindbloom has a Color Space viewer
00:14:30 Adobe RGB (1998)
00:15:50 Why not ProPhoto RGB?
00:16:20 Preparing some test shots in the lab
00:16:59 Comparing sRGB and Adobe RGB camera setting
00:18:42 Conclusion – stick to sRGB
00:19:34 Converting between color spaces
00:20:06 Intent: relative colorimetric or perceptual?
00:23:10 Winding down
After a too long summer break I give you a preview of one feature in the next version of GIMP – the unified transformation tool. It combines the tools for moving, rotating, scaling, shearing and for changing the perspective in one tool with a nice and sleek user interface.
The UI design has been done mostly by Peter Sikking. He has also had his hands in the nice free selection tool design.
This unified transformation tool shall be used with visual feedback on the canvas. The old tool will stay around for work where numbers are important. So this is not a replacement but an addition.
00:00:00 General rumblings
00:01:20 GIMPMagazine 4
00:02:26 GIMP 2.9
00:02:26 The Transform Tools of 2.8
00:04:00 Loss of sharpness – unavoidable with transformation
00:04:35 The new Unified Transform Tool UI
00:07:50 Better results due to only one calculation
00:09:00 Peter Sikking, UI architect
00:10:20 The UI design determines your work flow
00:10:41 No replacement for the traditional tools
00:11:33 Final words
00:11:50 End of video
There was no show for quite some time – and there will be a gap until the end of summer. I move back to Bremen – and that takes a lot of time and creativity away. But in Bremen I will have nearly 2 hours more time each day, because I can walk to school and don’t need to ride the famous Berlin S-Bahn Ring Line.
In the meantime I have a challenge for you! Present the place where you live to us – but look down on the sidewalk for that! The best results will be published in the GIMP Magazine #5 and of course here on the blog. The exact rules are below.
This Challenge is a perfect rip off from a challenge by Andrés (Twitter)(Website), an illustrator from Buenos Aires, in the now closed forum of Tips from the Top Floor. Make a mosaik of images of the sidewalks in your city and try to transport the atmosphere.
This is my take on the Silvio-Meier-Strasse around the corner from my flat in Berlin.
Make a mosaic of at least 3×3 images.
All images have to be shot straight down
All images are in the same scale, use the same distance to the ground and the same focal length.
All images have to be linked to each other in their theme by being from one city, one journey …..
Publish your image online and post a link to it before September 1st in the comments to this blog post.
License your image as CC-BY or better and allow this site and the GIMP Magazine to publish your image under CC-BY (here) or CC-BY-SA (GIMP Magazine).
Rules 1 to 4 may be broken, 5, 6 and 7 have to be followed exactly.
You may download the template for my version from above or build your own one. You are free to make other forms than a square – circles or a spiral anyone?
The video uses chapter marks, you can jump between TOC entrys!
00:00:00 Pause until end of August
00:02:05 A contest for you – introduction
00:03:42 The contest rules
00:04:50 My example
00:06:04 Selecting the images
00:08:00 Scaling down and exporting in Shotwell
00:08:40 Calculating the image size
00:09:30 Create the file
00:10:20 Save as XCF.gz – compressed to save space
00:11:05 Creating a “Contact Sheet” for reference with Imagemagick
00:13:00 Make a movable layer mask with “multiply mode”
00:16:00 Building a stack of layer groups and fill it with images
00:23:00 Filling images into the layer stack
00:26:45 Isolate the layer groups with “lighten only mode”
00:27:55 What do these layer modes do? Blackboard explanation
00:33:08 The last image – a Memory to Edith and Tina Wolff
00:34:30 Fine tuning the mosaic – exchange images
00:36:08 Adjusting contrast between the images with the curves tool
00:39:20 THE CHALLENGE
00:41:05 Variations: Soften the borders between fields
00:43:08 Final words about the Challenge
00:44:15 Exporting and scaling down for publication
00:45:45 End of video
In the last Episode I looked under the hood of JP(E)G and PNG. This time it gets a bit more practical – which is better for what?
I tackle two examples from the GIMP Magazine web site and test, if they would be better saved as JPG or PNG. The Plugin “Save for Web” is really usefull for this task.(The image for this blog entry is a PNG by the way, showing JPG compression artifacts. As a JPG it would be five times the size. )
I “developed” a method for comparing two layers – just set the top layer mode to “difference”, make a new layer from visible and check that with the threshold tool for pixels, that are not completely black. After locating the problematic zones in an image with this tool, one can decide what settings are “good enough”.
Conclusion: It depends. It depends on the file, your use case, your level of “good enough” and your compassion for people on a mobile device in EDGE-Hell.
The show starts with a little extension of the last show, Pascal mentioned some options for saving a JPG file that I had overlooked.
00:00:00 Start of video
00:01:00 Progressive mode in JPEG
00:04:09 Progressive mode is not fully supported by browsers
00:04:23 Optimized mode
00:06:17 The quality setting
00:07:09 GIMPMagazine and MTG header image – PNG or JPG?
00:09:23 Checking for quality loss in JPG
00:10:03 Comparing two layers with difference mode
00:10:48 Using the histogram for analysis of the amount of difference
00:11:25 Locating the differences
00:13:50 Trying 85, 75 and 90 as quality settings
00:16:13 When in doubt, compare different settings
00:16:36 Save your work as XCF.GZ
00:17:12 Second example – a drawing
00:23:19 Stay at 4:4:4 for subsampling with photos
00:25:16 Final words of wisdom
00:26:07 End of video
This is an episode completely in “Beginners Level”, some of you have asked for such a thing. I go through the editing of an image and cover a lot of topics. Nothing really in depth, but you should be able to work your way through other material after viewing this one.
I start with a short tour through the user interface of GIMP, you find more about that in the GIMP documentation and other places. In between there is a bit about saving vs. exporting an image – without the nasty and pointless discussion.
The image itself has to be rotated a bit, cropped, treated with a bit of curves, burned, and dodged, given more omphh with a layer in overlay mode that of course has to be modified with a layer mask. Finally the image will be scaled down, sharpened and exported as a JPEG while the original XCF file is conserved. Quite a tour – so I needed nearly an hour.
(I’ll update the links here later.)
00:00:56 Comments about the GAP problems
00:01:43 This episode is for beginners
00:02:58 Currywurst and Friedrichshain
00:04:18 The user interface – a short tour
00:04:35 The window header and saving into XCF
00:05:30 Exporting an image as JPG or PNG
00:06:50 Fullscreen and single window mode
00:07:20 Menues, Toolbox, Docks, Tabs
00:09:23 The image area with the canvas, rulers, sliders and buttons
00:10:20 Moving around in the image and zooming
00:12:00 Single window mode vs. multi window mode
00:13:01 TAB to switch the Toolbox and Docks on and off
00:13:32 The image – back story
00:15:30 What has to be done – making a plan
00:16:40 Rotate the image to straighten it
00:19:17 Cropping to a 3:2 aspect ratio
00:19:57 Inside Out Cropping
00:22:50 Make a backup layer
00:23:20 Curves Tool for contrast changes
00:27:30 Burning and Dodging with a layer in Soft Light Mode for local brightness changes
00:30:50 An extra layer for notes
00:33:30 Burning and Dodging
00:38:00 The Smudge Tool
00:41:27 Increasing contrast with a layer copy in Soft Light Mode
00:43:30 Adding a layer mask to apply the effect selectively
00:45:50 Softening the layer mask with a Gaussian Blur
00:47:45 Saving the image
00:48:03 Reducing the size for the Web
00:51:38 Exporting to JPEG
00:53:45 End of video
This episode is about using GAP, the GIMP Animation Package, and “The Book of GIMP”. I walk through one of the tutorials of the book and create a multi layered animation that will be used in a cleaned up form for these videos. I can not praise the book enough, you can read more in a former blog post. GAP showed some flaws, but this may be the problem of the Debian package that I used.
“The Book of GIMP” has also a reference part. I compare that to the official GIMP documentation while looking for information about the Convolution Matrix.
Before all that I tell you about a GIMP plugin for exporting a layer as a PDF file and I defend my new camera – 36 Megapixels may not be too much, they only show the limits of the lenses….. Cameras with smaller sensor sizes of course hit a barrier with more and more MP.
The next episode will have animated lower thirds and a proper automatically generated title screen. 😉
00:00:14 GIMP Magazine #3
00:01:20 Plugin for PDF export of layers
00:01:48 Are 36 Megapixel too much? (Nikon D800)
00:04:08 Where are 6 Megapixels enough? Sensor sizes
00:05:40 The Book of GIMP review
00:07:12 Testing the animation chapter
00:08:27 GAP – Moving Along a Path
00:10:12 New image from template and transparent background
00:11:50 Planning the animation
00:12:16 Building a dummy
00:13:40 Selecting the border of a selection
00:15:55 Make a new image out of a layer
00:17:10 GAP: Duplicate a layer 20 times
00:18:00 GAP: Move Path Tool
00:28:50 GAP: VCR Playback
00:29:30 GAP: Exporting an animation
00:31:40 The Manual part of “The Book of GIMP”
00:32:00 “The Convolution Matrix” compared with docs.gimp.org
00:35:30 Help to improve the documentation!
00:36:00 The printed book and the final verdict