PNG has full support for partial transparency and is currently the preferred format. You can use `Layer>Transparency>Semi-flatten to fill the transparency of these edge pixels with a new color (the color of the background on which the GIF will be used). GIF supports binary transparency (all opaque or all transparent) so your semi-transparent edge pixels are going to be altered.Color to alpha will be applied to the background and the edge pixels, where it matters. The pixels inside the subject, bieng excluded from the selection, won't be altered. If the image is dirty (JPEG artifacts), growing the selection by two or three pixels can be necessary. On a clean image (PNG, with no JPG history) you don't need to grow by more than one pixel. Select>Grow the selection so that it covers the anti-aliasing pixels.Use the wand to select the background.So if you apply the technique above these parts become transparent (or partially transparent). In the general case, the subject may have parts that are close to the color of the background. Gimp 2.10 works in "linear light" and has no such problems. You will notice that in the 2.8 results, there are darker pixels that are due to Gimp 2.8 working on gamma-corrected values (the result is still vastly better than the jagged edges you get with simpler methods). If you remove white from gray, you get a very transparent black pixel and not a not-so-transparent dark gray pixel, because among several solution Gimp picks the most transparent one.įor instance, using Color-to-alpha to remove the red gives this: If you remove red from purple, you get a semi transparent blue, because semi-transparent blue over red produces purple. They both replace the pixel by the most transparent pixel, which, put over the removed color, re-produces the initial color. Color erase mode, as a paint tool mode, or since Gimp 2.10 as a layer blend mode.In Gimp there are two ways to achieve this: The good solution is to replace the background color by transparency, in proportion of its contribution to the color mix. If you then bluntly Delete, you either get a halo with the color of the removed background (Threshold 15) or a jagged edge (Threshold 100) or both: When you use the color selector or the fuzzy selector, these pixels are either selected fully (if they are close enough) or not at all, depending on threshold. These pixels have a color which is a mix of the background color and the subject color. Chartered IT Professional (CITP) in the specialist area of solution development and implementation.On CGI (logos, text), the smooth edges are produced with anti-aliasing pixels. Member of the Irish Computer Society (MICS). Currently in Chartered Accountants Ireland's ACA program, FAE level. (Hons) Computing and Mathematics 2001, NUI, Galway. Provides an outsourced CTO resource and other consultancy via Open Solutions (including to INEX above).ī.Sc. Likes to talk - see my previous talks and presentations. Creator of many PHP applications - see the projects page. Live with a number of telcos - see Island Bridge Billing Systems.Įxpert PHP programmer, trainer, interviewer and consultant. IXP advocacy and consultant in both commerical and pro bono capacities.Ĭreator of a SaaS service bringing telecom and utility billing into the 21st century. Project manager and lead developer of IXP Manager, a free and open source platform powering over 200 IXPs around the world. Outsourced IXP expert, management team and operations team with INEX, the internet peering point for the island of Ireland. I live in Dublin, Ireland with my wonderful wife and darling daughter.Ĭo-founder of Island Bridge Networks - a company specialising in internet infrastructure providing mission critical network engineering, system administration, VoIP and development services to the ISP market. Thoughts, ramblings and rants of a husband, father, network engineer, sysadmin, coder, company owner, employer, accounting geek, sci fi fan, political anorak, impatient grump.
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