Why flatten layers

Likewise, combining the layers can be useful when you have an exceedingly large number of layers in your document and you want to, and can afford to, combine some of them to reduce the number and make the Layers Window more organised.

One of the major differences between the two options is the different effects each of them has on the transparent areas of your document. To summarise, the Merge Layers command preserves any transparency within the layers that are merged, whilst the Flatten Image command causes Photoshop to fill any transparent areas with the color white. As you can see in our Layers Window , we have simply opened a document that consists of three separate layers- each of them containing a single circle on a transparent background.

Here is what our document looks like before merging the layers. As you can see, the three circles sit on a transparent background which, in Photoshop and other applications, is by default represented by a checked pattern of white and gray.

Note that the second method will only work if you want to select and merge a group of layers that are consecutive in the Layers Window. You should then see that all the layers you want to merge in our case, this was all of them have been highlighted with a lighter gray color, indicating that they have been made active. With all the layers selected, simply right-click on one of them in the Layers Window and select Merge Layers from the list that appears as a result.

You will then notice that all the layers have been combined into one! Since we merged the layers rather than flattening the image, notice that the transparency within the merged layers has been preserved.

In our example, the circles still sit on a transparent background. This is because the Merge Layers command does not merge all the layers into a background layer, so the transparency is preserved. As you can see, we are using the same document, so this is what it looks like before merging the layers. The circles are all on their own layer and all sit on a transparent background.

Next, we will go ahead and flatten the image. This automatically combines all the layers, so you do not need to worry about selecting them all. This will combine all the visible layers within your document into a single background layer, as you can see in the Layers Window.

This time, do you notice a difference in the appearance of the document? The background is no longer transparent but has instead been filled with white. This is because the Flatten Image command does not preserve transparency since the layers are combined to form a background layer which is white by default.

So, if you are looking to preserve the transparency of any empty areas within your document, then you should always opt for the Merge Layers feature. The second major difference between the two commands is that the Merge Layers function lets you select which layers are combined whilst the Flatten Image function automatically combines all the visible layers within your document into a background layer.

So, if you want to only combine a certain group of two or more layers within your document, then you should definitely use the Merge Layers command instead of the Flatten Image one. Another thing to note about which layers are combined upon choosing each command is that the two have different effects on hidden, or invisible, layers.

All layers in Photoshop will be visible by default. However, you can make layers invisible by clicking on the eye icon as circled below next to their respective titles in the Layers Window.

Only after saving my docx files as doc files and then into pdf files Lulu accepted them. The reason was on me? If so, please, tell me what to do in order Lulu to accept my pdf files coming from docx files. Thank you. Monk Damaskinos. Unfortunately, trouble shooting an issue like that is best suited for our Support Team.

My best suggestions before reaching out to Support would be to ensure your version of Word is fully up to date and that you are following the procedure for that version it does vary depending on the edition of Word you use to export to a print-ready PDF.

The help article I linked above includes our presets for Adobe Distiller, if you choose to go that route. As a newspaper publisher, I have received ads in the PDF format and I learned early on — the hard way! I learned to take a screen-shot of what I received to send back for approval. That catches missing elements and font substitutions. A simple way to rasterize a file — I do it with all my Lulu book covers — is to first save the design as a PDF. I use a MAC, if that matters. Print Files Done Right Lulu—and all the other publishers out there—like to tell would-be authors how easy it is to create a book.

What Are Layers? Share This Post! Connect and share knowledge within a single location that is structured and easy to search. I am trying to understand the role of the Flatten function in Keras. Below is my code, which is a simple two-layer network. It takes in 2-dimensional data of shape 3, 2 , and outputs 1-dimensional data of shape 1, 4 :.

This prints out that y has shape 1, 4. However, if I remove the Flatten line, then it prints out that y has shape 1, 3, 4. I don't understand this. From my understanding of neural networks, the model. Each of these nodes is connected to each of the 3x2 input elements. Therefore, the 16 nodes at the output of this first layer are already "flat". So, the output shape of the first layer should be 1, Then, the second layer takes this as an input, and outputs data of shape 1, 4.

So if the output of the first layer is already "flat" and of shape 1, 16 , why do I need to further flatten it?

If you read the Keras documentation entry for Dense , you will see that this call:. So, if D x transforms 3 dimensional vector to d vector, what you'll get as output from your layer would be a sequence of vectors: [D x[0,:] , D x[1,:] , In order to have the behavior you specify you may first Flatten your input to a d vector and then apply Dense :. EDIT: As some people struggled to understand - here you have an explaining image:. This is how Flatten works converting Matrix to single array.

Flattening a tensor means to remove all of the dimensions except for one. This is exactly what the Flatten layer does. If we take the original model with the Flatten layer created in consideration we can get the following model summary:. For this summary the next image will hopefully provide little more sense on the input and output sizes for each layer. The output shape for the Flatten layer as you can read is None, Here is the tip. You should read it 1, 48 or 2, 48 or In fact, None on that position means any batch size.

For the inputs to recall, the first dimension means the batch size and the second means the number of input features. A flatten operation on a tensor reshapes the tensor to have the shape that is equal to the number of elements contained in tensor non including the batch dimension. Note: I used the model. It is rule of thumb that the first layer in your network should be the same shape as your data.

For example our data is 28x28 images, and 28 layers of 28 neurons would be infeasible, so it makes more sense to 'flatten' that 28,28 into a x1. Instead of wriitng all the code to handle that ourselves, we add the Flatten layer at the begining, and when the arrays are loaded into the model later, they'll automatically be flattened for us.

So there's an input, a Conv2D, MaxPooling2D etc, the Flatten layers are at the end and show exactly how they are formed and how they go on to define the final classifications Flatten make explicit how you serialize a multidimensional tensor tipically the input one. This allows the mapping between the flattened input tensor and the first hidden layer. If the first hidden layer is "dense" each element of the serialized input tensor will be connected with each element of the hidden array.

If you do not use Flatten, the way the input tensor is mapped onto the first hidden layer would be ambiguous.