I've searched high and low and finally hit upon alpha channels, but I don't know how to configure an alpha channel to suit my needs. I'm trying take this image...    ...And turn it into this. As you can see the top portion is 100% opaque, and the bottom is 0%. So its a kind of "alpha mask". How can I do this with Photoshop or Gimp or whatever, and save it into a 32-bit PNG?    I'm not simply trying to "cover" or "mask" my image like . I'm trying an alpha mask which is a whole different ballgame.
Last year I hired someone to do some work for our website but accidentally lost the PSD files since then. It's a fairly basic concept but I am fairly inexperienced with using masks.  How can I create the black circular gradient area as shown in this image below? I need to get as close as possible where it matches existing images on the site, why I am hoping its not too hard.  Thank you!
Numerical Approximation of Differential Equations with Midpoint Method For a physics major, what are the best books/references on Greens functions for self-studying?  My mathematical background is on the level of Mathematical Methods in the physical sciences by Mary Boas. How to know if Mac OS X machine is being remotely viewed? Why am I constantly running out of space on my Galaxy S2? Why can't I destroy or place blocks? I'm playing on a Survival world with cheats on, "easy" difficulty, and at night in-game. I didn't have a sword or anything to make a sword with, and I was starving, so I switched to Creative to give myself a stack of food and a bed to set my spawn point. When I switched back to Survival, I couldn't destroy or place blocks. I'm on single player, and my Internet is fine, and I can destroy blocks still if I switch to creative. I've tried resetting the button one, and reloading the map, and it still doesn't work. I've even tried deleting everything I gave myself in Creative. This happened before on a different world and I ended up deleting it.  This only happens on this world. How do I fix it?  If I know I'm in the correct game mode, what else can cause this?  Are there different causes in multiplayer? How to prove $\operatorname{Tr}(AB) = \operatorname{Tr}(BA)$? there is a similar thread here , but I'm only looking for a simple linear algebra proof. Should the first word after a colon be capitalized? Are "w/o", "w/", "b/c" common abbreviations in the US? When and how do we use the different kinds of brackets/parentheses&nbsp;— (){}[]&nbsp;— while writing English (not code)? Pandemic, Global Epidemic, Epidemic, Endemic I really want to hear from the experts the definitions of all 4 terms especially whether global epidemic is equivalent to pandemic. Or should this question be directed to the epidemiologist?   Pandemic Global Epidemic Epidemic Endemic   I have Googled the terms and I understand the definition of 1), 3) and 4). In short the definition is based on geographical location and scale of outbreak, Pandemic is an outbreak of disease on a global scale (e.g. HIV). Epidemic is an outbreak of disease on a localised area. Endemic is a disease in a localised area. However, a definition for Global Epidemic is not available online.  Recently, WHO mentioned that "“It is important to put this on the table: this virus(Covid19) may become just another endemic virus in our communities, and this virus may never go away,” WHO emergencies expert Mike Ryan told an online briefing." Isn't covid19 considered a pandemic since it is on a global scale and is spreading rapidly?  Another term that I come across often is Global Epidemic. For example in the WHO website, HIV is listed as Global Epidemic. Does that mean Pandemic and Global Epidemic are the same? How does Intel Turbo Boost work? If you have a java.io.InputStream object, how should you process that object and produce a String?    Suppose I have an InputStream that contains text data, and I want to convert it to a String, so for example I can write that to a log file.  What is the easiest way to take the InputStream and convert it to a String?  public String convertStreamToString(InputStream is) {     // ??? } Do Cleric's domain spells add slots? I'm a little bit confused with the whole spell system and additions to them. If I pick for instance Tempest Domain Spell, are the spells additional to the other ones? (2 at level 1) So do that make it 3 spells? Does the domain add slots too?  And also, I've read about people choosing multiple domains, is that possible? I have a skyscraper building but I only want the glass in the texture to be glossy.  How would I accomplish this?    Ok, I have done a test and here are the results.  Here is the original:   here is an adjusted image Auto-expand TAB character in code formatting Related:       Note that this question, while related, is not the same as the ones linked.  In many cases, when people put code into questions or answers, they copy/paste the code from their editor.  If their editor is using tab characters, the formatting will be broken after the post is submitted.  For example, if a code is indented using TAB characters, then one TAB character in the beginning of a line will be treated as one level of indent and align with the left edge of the code, effectively indenting equally to 4 spaces.  However in the post editor it looks indented twice - the same as 8 spaces.  I often edit other people's posts to improve code formatting and I find this TAB issue being the biggest annoyance.  Most of the times (I think) on SO, we use 4 spaces to format/indent the code.  I think it would be an easy thing to auto-expand TAB characters inside &lt;code&gt; blocks by replacing them with 4 spaces when the post is submitted. Is there a way to set app-specific volume? Constrains relationship I have the following design. Each user has it's own contacts, it's own hosts and assign those to a domain which belongs only to him.   I want to insure that the host you assign to the domain belongs to the user that domain is assigned to.  Is it something that I have to insure in my application logic?  If I set domains.user_id foreign key to reference host.user_id and user_id.id does it eliminate my issue?    By the way can anyone suggest me a better design for my schema? What are the best books to study Neural Networks from a purely mathematical perspective? I am looking for a book that goes through the mathematical aspects of neural networks, from simple forward passage of multilayer perceptron in matrix form or differentiation of activation functions, to back propagation in CNN or RNN (to mention some of the topics).  Do you know any book that goes in depth into this theory? I've had a look at a couple (such as Pattern Recognition and Machine Learning by Bishop or Deep Learning by Goodfellow, Bengio and Courville) but still have not found a rigorous one (with exercises would be a plus). Do you have any suggestions? Allow sound file uploads in questions and answers? Should Stack Exchange introduce the ability to upload embedded sounds (maybe via HTML5/Flash, whichever the user has) as part of questions and answers to Stack Exchange?  It could require a certain amount of rep to stop new users from doing it frivolously.  My rationale behind this is the new language &amp; usage sites.  I often find myself thinking that it might be helpful, when discussing a regional dialect or something, for the person answering to just pronounce what they're trying to describe in words. How to read a csv file and use the values as x and y points in blender?