This is one of the ways you can decode Pixel colors out of the integers you get from Android Pixels.<\/p>\n
ARGB_8888, stands for Alpha, Reg, Green, Blue. The 8’s stand for the number of bits per channel.<\/p>\n
In Android, signed 4 bytes = 32 bits = 8bits + 8bits + 8bits + 8bits.<\/p>\n If you had an If you’ve done web programming and played with rgb colors and you didn’t know about this, now it all should click on how your web browser represents colors, except in HTML you don’t deal with the alpha value in the front. On Android’s XML you do.<\/p>\n In bits (binary), the If you wanted to look at the entire number in binary\/bits, it’d be something like this (leaving spaces for visual help):<\/p>\n So if you wanted to get the red<\/em> channel ( So, we shift 16 places to the right, we’d get rid of the 2 bytes on the right side and end up only with the left half<\/p>\n Since we only care about those 8 bits on the right, we do an “&” (bitwise “and”) against So with simple right bit shifting and “& 0xff” of the shifted value we can extract the values per channel.<\/p>\n This class also features a “multiplyByFloat()” function, which I was using to multiply to each channel as I was operating with convolution kernels while playing with image filters.<\/p>\n [pastacode lang=”java” manual=”%2F**%20ARGB_8888%20Pixel%20abstraction%20*%2F%0Apublic%20static%20class%20PixelARGB_8888%20%7B%0A%20public%20final%20byte%20a%3B%0A%20public%20final%20byte%20r%3B%0A%20public%20final%20byte%20g%3B%0A%20public%20final%20byte%20b%3B%0A%20public%20final%20int%20intVal%3B%0A%0A%20public%20PixelARGB_8888(final%20int%20argb32bitInt)%20%7B%0A%20%20a%20%3D%20(byte)((argb32bitInt%20%3E%3E%2024)%20%26%200xff)%3B%0A%20%20r%20%3D%20(byte)((argb32bitInt%20%3E%3E%2016)%20%26%200xff)%3B%0A%20%20g%20%3D%20(byte)((argb32bitInt%20%3E%3E%208)%20%26%200xff)%3B%0A%20%20b%20%3D%20(byte)(argb32bitInt%20%26%200xff)%3B%0A%20%20intVal%20%3D%20argb32bitInt%3B%0A%20%7D%0A%0A%20public%20PixelARGB_8888(byte%20a%2C%20byte%20r%2C%20byte%20g%2C%20byte%20b)%20%7B%0A%20%20this.a%20%3D%20a%3B%0A%20%20this.r%20%3D%20r%3B%0A%20%20this.g%20%3D%20g%3B%0A%20%20this.b%20%3D%20b%3B%0A%20%20intVal%20%3D%20(a%20%3C%3C%2024)%20%2B%20(r%20%3C%3C%2016)%20%2B%20(g%20%3C%3C%208)%20%2B%20b%3B%0A%20%7D%0A%0A%20public%20static%20int%20multiplyByFloat(float%20factor%2C%20int%20arg32bitInt)%20%7B%0A%20%20return%20multiplyByFloat(factor%2C%20arg32bitInt%2C%20false)%3B%0A%20%7D%0A%0A%20public%20static%20int%20multiplyByFloat(float%20factor%2C%20int%20argb32bitInt%2C%20boolean%20multiplyAlphaChannel)%20%7B%0A%20%20PixelARGB_8888%20original%20%3D%20new%20PixelARGB_8888(argb32bitInt)%3B%0A%20%20byte%20alpha%20%3D%20original.a%3B%0A%20%20if%20(multiplyAlphaChannel)%20%7B%0A%20%20%20alpha%20%3D%20(byte)(original.a%20*%20factor)%3B%0A%20%20%7D%0A%20%20PixelARGB_8888%20multiplied%20%3D%20new%20PixelARGB_8888(alpha%2C%20(byte)(factor%20*%20original.r)%2C%20(byte)(factor%20*%20original.g)%2C%20(byte)(factor%20*%20original.b))%3B%0A%20%20return%20multiplied.intVal%3B%0A%20%7D%0A%7D” message=”” highlight=”” provider=”manual”\/]<\/p>\n","protected":false},"excerpt":{"rendered":" This is one of the ways you can decode Pixel colors out of the integers you get from Android Pixels. ARGB_8888, stands for Alpha, Reg, Green, Blue. The 8’s stand for the number of bits per channel. In Android, signed int‘s are used to represent pixel’s alpha\/color information. Since Android’s language of choice is java, […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":true,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[15],"tags":[1549,1437,1550,1548,583,1272],"class_list":["post-3616","post","type-post","status-publish","format-standard","hentry","category-code","tag-argb","tag-code","tag-filers","tag-image-processing","tag-java","tag-pixel"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p5Unzf-Wk","jetpack-related-posts":[{"id":2887,"url":"https:\/\/www.gubatron.com\/blog\/android-changing-textview-alpha-transparency-across-different-target-sdks\/","url_meta":{"origin":3616,"position":0},"title":"Android: Changing TextView alpha transparency across different target SDKs","author":"gubatron","date":"November 30, 2012","format":false,"excerpt":"Sometimes you may need to make a TextView (label) look a little transparent to make emphasis on other parts of your UI. The .setAlpha() function on TextView is not supported after later in the SDK. Here's a static workaround you can place on some sort of UIUtils class you may\u2026","rel":"","context":"In \"Android\"","block_context":{"text":"Android","link":"https:\/\/www.gubatron.com\/blog\/tag\/android\/"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":2138,"url":"https:\/\/www.gubatron.com\/blog\/java-how-to-create-dynamic-pngs-jpgs-gifs\/","url_meta":{"origin":3616,"position":1},"title":"Java: How to create dynamic PNGs, JPGs, GIFs.","author":"gubatron","date":"February 14, 2010","format":false,"excerpt":"Sometimes you need to create graphics, or compose images and have them saved as regular PNGs, JPEGs or GIFs. Here's a quick and dirty reference of how to do it with BufferedImages, Graphics2D and javax.imageio.*. Very straightforward. [java] import java.awt.Color; import java.awt.Graphics2D; import java.awt.image.BufferedImage; import java.io.File; import java.io.IOException; import javax.imageio.ImageIO;\u2026","rel":"","context":"In "Code"","block_context":{"text":"Code","link":"https:\/\/www.gubatron.com\/blog\/category\/code\/"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":1269,"url":"https:\/\/www.gubatron.com\/blog\/how-to-make-a-quick-dirty-hexviewer-updated\/","url_meta":{"origin":3616,"position":2},"title":"How to make a Quick & Dirty HexViewer – Updated","author":"gubatron","date":"April 20, 2009","format":false,"excerpt":"After I received comments from ispak on Flickr I made a few fixes. ispak pointed out that it was a bad idea reading one byte at the time, also I had a gay ass try\/catch that didn't catch any exception :p So now I read 16 byte chunks, and I\u2026","rel":"","context":"In "Code"","block_context":{"text":"Code","link":"https:\/\/www.gubatron.com\/blog\/category\/code\/"},"img":{"alt_text":"HexViewer - r2","src":"https:\/\/i0.wp.com\/farm4.static.flickr.com\/3486\/3458529439_31357e0afe_o.png?resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/farm4.static.flickr.com\/3486\/3458529439_31357e0afe_o.png?resize=350%2C200 1x, https:\/\/i0.wp.com\/farm4.static.flickr.com\/3486\/3458529439_31357e0afe_o.png?resize=525%2C300 1.5x"},"classes":[]},{"id":1928,"url":"https:\/\/www.gubatron.com\/blog\/droid-vs-nexus-1-who-can-calculate-md5-faster\/","url_meta":{"origin":3616,"position":3},"title":"Droid vs Nexus 1: Who can calculate MD5 faster?","author":"gubatron","date":"May 21, 2010","format":false,"excerpt":"Nexus 1 indeed. 17 files get their MD5 calculated on the Droid and 17 files get their MD5 hash calculated on the Nexus 1 Nexus 1 pwns. Here's the code in case you're curious. [java] public void onClick(View v) { _logTextView.setText(\"MD5 Benchmark on \" + Build.DEVICE + \"nn\"); if (GlobalVariables.APP_CONTEXT\u2026","rel":"","context":"In "Android"","block_context":{"text":"Android","link":"https:\/\/www.gubatron.com\/blog\/category\/android\/"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":2142,"url":"https:\/\/www.gubatron.com\/blog\/how-to-convert-android-gps-coordinates-into-xy-coordinates\/","url_meta":{"origin":3616,"position":4},"title":"How to convert Android GPS coordinates into X,Y coordinates.","author":"gubatron","date":"December 30, 2010","format":false,"excerpt":"Without further math bullshit about all the conversion systems, when you have a bunch of Android GPS coordinates (which are compatible with Google Earth and Google Maps), and you want to draw them on a finite 2D plane, here's what worked for me. [java] int x = (int) ((PLANE_WIDTH\/360.0) *\u2026","rel":"","context":"In "Android"","block_context":{"text":"Android","link":"https:\/\/www.gubatron.com\/blog\/category\/android\/"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":2047,"url":"https:\/\/www.gubatron.com\/blog\/map-function-in-java\/","url_meta":{"origin":3616,"position":5},"title":"Map function in Java","author":"gubatron","date":"August 31, 2010","format":false,"excerpt":"I read on some email signature something along the lines of: \"If I had a dollar for every for(int i=0; i < size; i++) { ... } I've written I'd be rich\" After coding on Android and learning about some of the tips for performance, like \"With an ArrayList, a\u2026","rel":"","context":"In "Code"","block_context":{"text":"Code","link":"https:\/\/www.gubatron.com\/blog\/category\/code\/"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]}],"_links":{"self":[{"href":"https:\/\/www.gubatron.com\/blog\/wp-json\/wp\/v2\/posts\/3616","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.gubatron.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.gubatron.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.gubatron.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.gubatron.com\/blog\/wp-json\/wp\/v2\/comments?post=3616"}],"version-history":[{"count":11,"href":"https:\/\/www.gubatron.com\/blog\/wp-json\/wp\/v2\/posts\/3616\/revisions"}],"predecessor-version":[{"id":3781,"href":"https:\/\/www.gubatron.com\/blog\/wp-json\/wp\/v2\/posts\/3616\/revisions\/3781"}],"wp:attachment":[{"href":"https:\/\/www.gubatron.com\/blog\/wp-json\/wp\/v2\/media?parent=3616"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.gubatron.com\/blog\/wp-json\/wp\/v2\/categories?post=3616"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.gubatron.com\/blog\/wp-json\/wp\/v2\/tags?post=3616"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}int<\/code>‘s are used to represent pixel’s alpha\/color information.
\nSince Android’s language of choice is java, these ints are 32-bit integers, each int<\/code> takes 4 bytes.<\/p>\nint<\/code> like 0xFFAABBCC<\/code>, each pair of letters on that hexadecimal would mean the following from left to right<\/p>\n{alpha=0xFF}{red=0xAA){green=0xBB}{blue=0xCC}<\/code><\/p>\n0xFFAABBCC<\/code> value would look like this:<\/p>\nalpha red green blue\n0xFF 0xAA 0xBB 0xCC\n255 170 187 204\n{0b11111111}{0b10101010}{0b10111011}{0b11001100}\n<\/code><\/pre>\n0b11111111 10101010 10111011 11001100 == 0xFFAABBCC == 4289379276\n<\/code><\/pre>\n0xAA = 170 = 0b10101010<\/code>) , you’d have to move the whole thing towards the right 16 places, and then compare it with only the rightmost 8 bits.<\/p>\n0b11111111 10101010\n<\/code><\/pre>\n0xFF=255=0b111111111<\/code> (all 8 rightmost bits set to 1)<\/p>\n0b11111111 10101010 &\n0b00000000 11111111\n====================\n0b00000000 10101010\n<\/code><\/pre>\n