It uses only CHW, and we’ll sum it up by saying it is faster. You may ask why! And the reason points to cuDNN which is what helps accelerate processing on GPUs. Tweak RGB to be BGR, which is encapsulated as this “C” payload, then tweak HWC, the “C” being the very same colors you just switched around. Essentially, you’re going to want to use CHW and make sure that step is included in your image pipeline. For CPU processing, this order is generally HWC. We can tinker with it’s underlying properties and as you saw above, swap colors quite easily.įor GPU processing, which is what Caffe2 excels at, this order needs to be CHW. What we see is on top of the cube, and manipulating the layers below can change what we view. These were data transformations that let us play with the image as if it were a cube. You might have noticed when we first loaded the image that we forced it through some interesting transformations. Now what!? What’s CHW, you ask? Well, there’s also HWC! Both formats come up in image processing.ĭigging even deeper into how image data can be stored is the memory allocation order. In the code block below we’ll be taking the image and converting to BGR order for Caffe to process it appropriately.īut wait, there’s more color fun… Caffe Prefers CHW Order title ( 'OpenCV, Caffe2 = BGR' )Īs you can see in the example above, the difference in order is very important to keep in mind. title ( 'Original image = RGB' ) # show the image in BGR - just doing RGB->BGR temporarily for display imgBGR = img #pyplot.figure() pyplot. float32 ) # test color reading # show the original image pyplot. #IMAGE_LOCATION = 'images/cat.jpg' # For Round 2 of this tutorial, try a URL image with a flower: IMAGE_LOCATION = "" # For Round 3 of this tutorial, try another URL image with lots of people: #IMAGE_LOCATION = "" # For Round 4 of this tutorial, try a URL image with a portrait! #IMAGE_LOCATION = "" img = skimage. # You can load either local IMAGE_FILE or remote URL # For Round 1 of this tutorial, try a local image. ![]() In many ways this decision helps in the long run as you use different computer vision utilities and libraries, but it also can be the source of confusion. Make sure the image data you’re passing around is what you think it is! Caffe Uses BGR Orderĭue to legacy support of OpenCV in Caffe and how it handles images in Blue-Green-Red (BGR) order instead of the more commonly used Red-Green-Blue (RGB) order, Caffe2 also expects BGR order. ![]() This would obviously throw off detection in your model. Below we show an example of how flipping between RGB and BGR can impact an image. Keep in mind when you load images from smartphone cameras that you may run into color formatting issues. When you pick a remote URL, make it easy on yourself and try to find a URL that points to a common image file type and extension versus some long identifier or query string which might just break this next step. ![]() ![]() If you want to try your own image, drop it in the images folder or use a remote URL. In this way, you’ll get to see what happens with a variety of image formats and some tips on how you might preprocess them. Just change the comment flags to go through each round of the Tutorial. In the code block below use IMAGE_LOCATION to load what you would like to test.
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