Throughout the course of searching for the perfect oriental carpet, or runner in this case, one may find it difficult to identify certain techniques which sellers use to capture the image of the rug on the floor, to a photograph on your monitor. Invariably, the majority of rug images posted online have some sort of augmentation techniques. To photoshop a carpet is not entirely frowned upon, as most of the time the intention is to color balance a poor exposure to true-to-life colors, or maybe even simply crop an image.
However, some sellers may have other intentions. In the case of a heavily curved runner (a strong bow in the middle) for example, it is not unusual for less reputable sellers to not only omit a written description, but also attempt to hide such physical characteristic of a rug. The reason for doing so has a great deal to do with the intensity of the process to fix such a bowed shape: It is time consuming, expensive, and not always guaranteed. From the standpoint of the seller, it is better to sell a rug as-is for at a lower price point rather than opt for a procedure which may or may not work. Conversely, from the consumer's perspective, what good is a "boomerang runner" in your hallway? When two corners of the runner are kissing one wall, and the center of the rug is crawling up the opposite wall, there's no real utility.
However, most sellers will not spend the time on a computer to alter images to create the illusion of a straight rug. This sometimes creates other distortions which may lead a buyer to recognize that photograph alterations had been made. Rather than generating a straight rug with computer alteration, trickery is usually implimented with one of several photograph and staging techniques as seen below.
Three Easy Tips on What to Look for in an Advertised Oriental Runner:
1: Beware of photographs where the image appears as though the camera was tilted to one side when taking the picture. One of the most classic ways to hide the severity of a curved runner is to frame it square in the viewfinder, then rotate the camera on the tripod slightly toward the outside bow toward the center of the rug. This creates the illusion that both ends are parallel, which adds to the perception that the rug is straight, when in fact it is not.
2: If you see a runner that has one or more small triangular "lumps" towards either the middle or one end of the carpet, the seller is probably attempted to manually correct the irregularity. This is done by placing the rug flat on the floor, then pushing the two opposing longer sides of the carpet towards the middle from either end to give the appearance of a straight and true carpet.
3: Finally, if you see a seller has photographed a runner or carpet in a different direction than the wooden floorboards run, they may be attempting to remove your ability to distinguish a straight line.
If it is important for the intended area to have a straight and square carpet, always be sure to send an e-mail to the seller explicitly asking if it is. If the seller fails to address your specific concern, the answer is not to call them up. Be sure they respond in writing, as this is both your right as a buyer, and may serve as written proof to dispute an item which is not received as advertised.
The above assessment does not take into consideration physical corrections which may be implimented to actually correct a curved runner. Take a look at "Starched Oriental Rugs: The Straight Truth" for additional information.
Take a look at some other techniques to check if a rug is straight, true and symmetrical.