Open-Source Paint Package for Windows

Introduction

Rendera is an open-source painting program for Windows. The tools, shapes, blenders, edge-wrapping, and cloning may all be combined to suit a particular need. The program is different in that brushstrokes are computed and rendered after being drawn. Some uses for Rendera include photo restoration, colorizing, making seamless tiles, etc.

Drawing a seamless tile

Download Rendera

Please post bug reports or comments on SourceForge, I will see them eventually.

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Source Code

Source code is provided under the terms of the GNU General Public License. A standalone executable is provided in the package.

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File Support

Only 24-bit BMP and JPEG images are supported, so paletted images will be saved in 24-bit color (but will look like the paletted image). For now, further conversion must be done in some other program.

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Preview Mode

Rendera allows reatime preview of indexed and grayscale modes. The internal image is always truecolor. Selecting "apply colors" will keep the changes permanent.

Truecolor

Grayscale

Indexed Color

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Color Quantization

Optimal palettes may be generated by selecting "create" under the palette menu. Rendera uses an approximation of Pairwise Clustering to produce high-quality images.

Original Image

4 Colors

16 Colors

256 Colors

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Painting

Almost all program functions (art tools, shapes, blending modes, wrapping, cloning, etc.) may be combined to achieve various effects.

Left Mouse - Paint

Right Mouse - Move Around

Wheel - Zoom In/Out

Brush Strokes

Watercolor Simulation

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Seamless Tiles

Enable the wrap mode and everything you draw will wrap around the edge. Image scaling can also wrap. The offset tool lets you interactively scroll the image.

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Retouching

Enable the clone tool, select a mirroring option and press space to set the clone target. Cloning works with everything else, including wrapping.

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Colorizing

Rendera features luminance-exact colorizing. This means you can recolor an image infinitely with no degradation. It also means that colorized images will look less phony.

Scanned Image

Colorized Result

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Effects

A number of special effects are available in Rendera:

Stretch Contrast - Uses optimal light/dark luminance values to adjust image contrast.

Normalize - Stretches luminance to maximum range.

Remove Dust - Filters dust from scanned images.

Multi-tone - Creates a monochromatic image using the current color.

Invert - Inverts RGB color values.

Noise - Adds luminance noise to image.

Enhance - Increases color saturation while retaining luminance.

Rotate Hue - Rotates hues around an imaginary color wheel.

Original Image

Enhance

Stretch Contrast

Multi-Tone

Rotate Hue

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Color Mask

This option is helpful for drawing sprites.

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Scale Image

Scales the image (with gamma correction) to the specified size. If scaling down, then the image will be mipmapped to provide a basic form of antialiasing. Wrapping is preserved if enabled.

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