Onekit Texture Converter is a freeware tool for 3D game developers. This tool converts PNG format images to JPG images, taking into account the alpha channel presence. However, it’s not all this tool can perform. There’re also available such features as output size managing and size correctness checking that are required in 3D game development.

What made this tool so necessary?

There are a lot of PNG to JPG converters available, but it was 3D game developers that this tool was created for.
In 3D game development, it is wise to use image formats without the loss of quality and the ones that bear the alpha channel for texture storing purpose. Say, it may be PNG format. This format supports some features that are hardly used today, like 16 bit per component (64 bit graphics). But what if you need to make the product that you release less in size? What can the developers that operate on a shareware market do about it? Or how can you make a little bit less a demo version of the game that you are going to issue soon? If you take into account that a lot of game developers use OGG and MP3 formats for sound storing (where you always have a loss of quality), then why not save some texture file space losing some image quality. It’s not many formats that you can choose from, so Onekit Texture Converter generates JPG files. Now it all depends on what is more important for you: the file size or the image quality. The converter searches for PNG files in the folder that you point to and upon performing necessary operations saves them to a different folder (that you set as well) as JPG files.
How can you store the alpha channel in a JPG format? This is the problem that Onekit Texture Converter successfully solves. It is square textures that are mostly used in 3D game development, that is textures with the equal width and height dimensions. In order to store the alpha channel in a JPG format you need to set “Save alpha if exist” in the Onekit Texture Converter dialog. The converter stores the texture and the alpha channel right beneath it. You can set the color component that stands for the alpha channel. It can be either Red, Green, Blue or Grayscale. Grayscale means that Red, Green and Blue components are stored together. You can set it in the “Alpha components” combobox. So as a result we get an image with height = (width * 2) dimensions that bears the alpha channel.
The JPG file won’t get much larger because of the alpha channel information, and since the alpha channel consists of just one component it is easier for JPG algorithm to compress such information than multi color images. And now it’s the game developer task to write a loader for such a texture – surely it‘s not a hard task to perform. This tool was developed using a freeware Independent JPEG Group library (http://www.ijg.org/).

Onekit Texture Converter features.

“PNG:” – here you can choose a folder to load PNG files from;
“JPG:” – here you set the folder to save JPG files to;
“JPG quality:” – here you set the JPG quality. Probably 70-85% is the best and most satisfactory quality level. Such quality settings can make the file size 5-10 times less then the original PNG file.
“Size maximum:” – here you set the size limit for the generated JPG file. This helps you control the size of the generated textures. There are several reasons to restrict the texture size. Say, the artist used large textures but you can’t use such dimensions in the game because it’s not enough memory on a PC platform that mentioned in the System Requirements. There is one more reason to make the texture size less. You may need to shrink the packet size and texture reducing might be the only possible way.
“Size division:” – here you can set the texture size division. If you set it to “1” then no division is performed, but if you set a different value the output texture size is decreased. If Size Division = 2, then a 512x512 texture will be saved as a 256x256 one.
“Scaling:” – here you choose a scaling method. Bilinear ? Bicubic are recommended.
“Blur alpha channel” – a slight alpha component blur is added, in case the alpha channel is present and stored in the JPG file. Use it only if you understand what you do.
“Save alpha if exist” – stores the alpha channel information right beneath the texture data.
“Default Config” – sets the default settings.
“Save Config” – saves the settings in the “HKLM\Software\Onekit\Textureconverter” registry key.
“Start Processing” – performs PNG to JPG conversion. Saves the configuration in the “HKLM\Software\Onekit\Textureconverter” registry key.
“Exit” – closes the application and doesn’t save the current settings.
Command line keys:
“/nogui” (“otc.exe /nogui”) – lets you start the processing automatically. In this case all the conversion settings are taken from the registry.

Practice.

There’s no need to make an artist or a 3D modeler create JPG textures. It’s okay for them to create and use PNG files. And still you can take the advantages of JPG files in a game after performing a PNG to JPG conversion with the help of Onekit Texture Converter. The artist may incorrectly set the texture dimensions. Say, he can use 1125x1224 textures. Onekit Texture Converter will easily reduce the dimensions to the ones required in 3D game development. In the above case the proportions will be set to 1024x1024.
In case a texture has incorrect dimensions, one of the following proportions will be used instead: 16x16, 32x32, 64x64, 128x128, 256x256, 512x512, 1024x1024, 2048x2048, 4096x4096, 8192x8192, 16384x16384.
Attention: due to a rational texture proportions principle, Onekit Texture Converter will always reduce texture dimensions to the closest ones used in 3D game development. Say, a 64x63 texture will be reduced to a 32x32 one.