Challenge
| Subject: | The Case of the Queen's Gambit | ↰ |
| Difficulty: | ●○○○○ | |
| Duration: | 1 minutes (estimated) | |
On 5-April-2020, Queen Elizabeth made a rare public statement about the coronavirus crisis. In the televised statement, she wore a green dress. Of course, it didn't take long for the internet to use the dress as a green screen for replacing content. She very quickly became a popular meme. Use Error Level Analysis to evaluate these pictures of the Queen. If you didn't know the backstory, could you still tell that the picture was altered? Similar textures should have similar compression properties and appear similar under Error Level Analysis (ELA). In addition, recompressing a JPEG multiple times (resaves) makes the ELA result appear dark. The original background and head are dark due to multiple resaves. The shirt logo stands out as bright compared to the rest of the picture, indicating the alteration. The jewelry also stands out, even though it existed in the original picture. What happened? The artist replaced the green fabric around the jewelry, causing a modification to the jewelry as well. This picture came from Twitter. Twitter resaves all pictures, removing metadata and lowering the overall image quality. In this case, the only alterations that still remain detectable comes from the outline around the shirt and the jewelry. The shirt was likely a low-quality image before being inserted into the picture, leaving the edges as the only high quality difference. Similar to Iron Maiden, the jewelry stands out because the fabric around the jewelry was changed. This picture also came from Twitter, so it was resaved at a lower quality. The green fabric was changed to black, and the re-encoding by Twitter likely removed any detectable changes. In contrast, the card on the shirt was a significant edit that even appears after the re-encoding by Twitter. Unlike the other two images, the artist selected around the jewelry, leaving them at a lower quality level (darker ELA) than the surrounding card alteration. Visually, you can see where the artist selected the green shirt, but did not fade the selection. You can still see the green from the shirt around the edges. The source picture has undergone multiple resaves. It started as a frame from a video. (A high quality video is usually a lower quality than a low quality photo.) The video frame was saved and then post-processed for inclusion by media outlets. This includes scaling the picture and saving it at a low quality. (JPEG % reports that this picture was last saved at 75%, but the cumulative quality degradation is less than 50%.) Most pictures presented by news outlets have been scaled, recolored, and post-processed for viewing in a web browser. They rely on lower quality images to reduce the file size, resulting in a faster loading time in your browser. This is not unusual and not an indication of deception. These pictures were found online: Green Queen: Screen frame as televised on 5 April 2020. Iron Maiden: vinzwarrenjr on Imgur Commander: @Dahie on Twitter Hearts: @emilianovinocur on Twitter | ||