lookup-tables

问题 I'm beginning to understand how to implement a fragment shader to do a 1D LUT but I am struggling to find any good resources that tell you how to make the 1D LUT in C++ and then texture it. So for a simple example given the following 1D lut below: Would I make an array with the following data? int colorLUT[255] = {255, 254, 253, ..., ..., ..., 3, 2, 1, 0}; or unsigned char I guess since I'm going to be texturing it. If this is how to create the LUT, then how would I convert it to a texture?

问题 In my database, many tables have the 'State' field, representing the state that, that particular entity falls in. I have been told that we should use Lookup tables for this kind of thing, but I am unsure of the exact mechanism. Can someone clarify these points? How is the integrity maintained? (i.e. how do I make sure that only the values from the state table go into the other tables?) Does the state name go into the other tables, or does the state id from the state table go into the other

问题 While writing a lookup-table related answer for another question I was reminded of something that I always wonder about: is it smart to locate a small amount of non-code data needed by a function right next to the function, instead of the traditional approach of putting it in another section? Let's say you have a small function, which uses a small, read-only, lookup table. The usual approach seems to be to locate the lookup table in a data section, such as .rodata which will generally place

问题 I'm looking for a nice easy way to find what sectors occupy a given file. My language preference is C#. From my A-Level Computing class I was taught that a hard drive has a lookup table on the first few KB of the disk. In this table there is a linked list for each file detailing what sectors that file occupies. So I'm hoping there's a convinient way to look in this table for a certain file and see what sectors it occupies. I have tried Google'ing but I am finding nothing useful. Maybe I'm not

问题 I found the lookup table here. The table is generated as a reverse bits table of 8 bits. I can not figure out why it works. Please explain the theory behind it. Thanks static const unsigned char BitReverseTable256[256] = { # define R2(n) n, n + 2*64, n + 1*64, n + 3*64 # define R4(n) R2(n), R2(n + 2*16), R2(n + 1*16), R2(n + 3*16) # define R6(n) R4(n), R4(n + 2*4 ), R4(n + 1*4 ), R4(n + 3*4 ) R6(0), R6(2), R6(1), R6(3) }; 回答1: First off a comment: This kind of thing is normally only done in

问题 I'm fairly new to Tableau, and I'm struggling in building some routines that could be easily implemented in Excel (though it would take forever for big sets of data). So here is the deal, consider a dataset with the following fields: int [id_order] -> id of the sales order (deepest level, there are only unique entries of id_order) int [id_client] -> as I want to know who bought it date [purchase_date] -> when the customer bought the product What I want to know is, for each order, when was the

问题 I am developing an application which includes filters and crop too. Here I am using cropping library. Here I used 8*8 luts like sample lut. Here I want to CROP the filtered image(8*8 lut) Here is the logic to crop the image. Bitmap cropbitmap = ivCropimageView.getCroppedImage(); Using this bitmap I generate a thumbnail bitmap like below. Bitmap thumbImage = ThumbnailUtils.extractThumbnail(cropbitmap, 190, 250); When I am trying to generate thumbnails for all filters then the thumbnails are

问题 I'm trying to find the best way to implement a QHash-like lookup table that uses multiple keys to return one value. I have read that the Boost library has similar functionality, but I would like to avoid this if possible. An example of what I would like to do is as follows (obviously the following pseudo-code is not possible): //First key (int) - Engine cylinders //Second key (int) - Car weight //Value (int) - Top speed MyLookup<int, int, int> m_Lookup m_Lookup.insert(6, 1000, 210); m_Lookup

问题 I'd like to create a table lookup formula that matches two columns. For instance, suppose I'd like to find the value of the Letter column at the row where the Type column is Biennial and the Result column is Warning . A B C 1 Letter Type Result 2 A Annual Exceeds 3 B Biennial Warning 4 C Biennial DevelopmentNeeded 5 D Biennial PartiallyMeets 6 E Annual Meets What would the formula look like to accomplish this? 回答1: The SUMPRODUCT() formula is really apt for situations where you want to lookup

问题 I am trying to make a simple LookUpTable based on an array of integers, where the idea is to have it calculated at compile time . Trying to make it possible to use it for any other future tables of various integer types I might have, I need it as a template . So I have a LookUpTable.h #ifndef LOOKUPTABLE_H #define LOOKUPTABLE_H #include <stdexcept> // out_of_range template <typename T, std::size_t NUMBER_OF_ELEMENTS> class LookUpTableIndexed { private: //constexpr static std::size_t NUMBER_OF