The 2 pictures are identical. It's not Flash, it's not the web browser.
The problem is Intel integrated graphics.
There is a "feature" on the Intel integrated graphics which Intel calls: "Display Power Saving Technology"
Based on my test, it saves nothing. The idea of the feature is to play with the contrast at a software level based on the content being displayed. The idea is that on dark content the screen increases the contrast, so you see better the content, and then, hopefully makes you decrease the brightness of the display, as you see things better or more easily. Cool idea in principal, sadly it's Intel, so its idiots that worked on it. Here is why I am saying this:
1- It works on REVERSE. It dims the screen color (contrast) on dark scenes, making you increase the screen brightness even more, defeating the entire purpose of "power saving". It is more like "power consuming". This was NEVER fixed. It affects all Intel integrated graphics of this generation CPU.
2- It is a software level adjustment. Adjusting colors properly at a software level, is VERY CPU taxing. So they are not doing it properly to minimize processing required (else it would defeat the purpose, of the idea that is great in principal). The result is however, a reduction in colors. If you open a picture editor and create a full screen gradient image (white to black, for example), you will see stepping, and not a smooth transition as you should.
The better news is that it disables itself when you are plugged it.
The good news, is that you can disable it completely!
The bad news, is that, the system which turns this feature on or off, if you are plugged in or not, is ALSO broken, where it tends to forget that you are plugged in, and turns it on regardless. So, you definitively want this feature disabled.
The bad news is that it ALSO tend to sometimes forget that you disabled it, and decides to enable it, and the only fix is restarting the system.
Don't you love Intel?
Yea. It sounds bad, but this is nothing new for Intel integrated graphics. Intel is most likely is outsourcing the development of it's drivers to India and/or China, which would explain the piss poor quality of it and the lack of any caring. And also, it would explain the lack of optimizations, like for example, if you have the Intel Control Panel menu items on the right-click menu, it takes more time to display than if you didn't. This shows that it does heavy CPU processing (probably loads stuff, not needed), at every right-click. And I can go on. You can disable it, but requires some registry tweaking 9basically remove Intel from the right-click menu)
So how to fix it, somewhat (due to bugs where it forgets that you disabled it, sometimes)?
-> Open the Intel HD Graphics Control Panel
-> Go under Power, then on "On Battery", then disable: "Display Power Saving Technology", and click "Apply".
-> Once done, go back, then go under Video, and make sure everything is set to "Application Settings". Then next to the "(<-)" (back) button, you'll see "Video", and a down pointing button, click on that.
-> A menu should pop-up. Now go through each of them and again make sure that no colors are being adjusted, and everything is on "Application Settings". Of course, Apply when done
-> Once all done, close, and restart your system.
This should solve your problem. If it does not, they are more things we can do.