Continued from In Texture Heaven: Part 1
Evening Up the Lighting
Because there were moments in the day where the sun did appear, this particular photograph shows a darker area at the top of the door caused by the lintel shadow and a more washed out brighter area at the base of the door caused by the more direct sunlight. Specific changes in lighting like this, from light to dark, can be adjusted by first creating an opposing gradient (dark to light) to form a mask and then adjusting the light levels through that mask. In Photoshop white depicts full effect and black no effect. So a gradient with white at the top and easing to black part way down the door will allow the lightening of the upper area of the door without affecting the lower area and the adjustment will fade off gradually so no “edge” to its application will be seen.
The gradient is applied using the Gradient Tool which sits alongside the Paint Tool in the Tools Menu.
A new layer is created above the current visible door layer and the gradient applied. Because the shadowing is coming slightly more from one side than the other the gradient is angled towards that side.
This gradient now needs to be turned into a mask and this is achieved by first switching from the Layers tab to the Channels tab. Here all the colour channels will be displaying their colour’s input into the gradient, this being the image resulting from the layers as they stand at present. Because equal amounts of red, green and blue are used for any greyscale colour from black through to white all channels appear the same and actually are carbon copies of the gradient. A mask (displayed as a feathered selection) can be created that uses this greyscale by holding down the Ctrl key and clicking on any one of the colours’ channel icons. Note that though the mask edge appears sharp it actually isn’t. The mask border only displays around areas that are allowing more than 50% of an effect through; the lesser areas are not bordered.
Returning to the Layers tab, the gradient layer can now be deleted leaving the mask sitting over the door layer (deleting the gradient layer does not deselect the mask). With the visible door layer selected the Levels dialog window is opened.
From the Levels dialog window the lighting is increased by moving the left hand slider inwards an appropriate amount, ensuring the effect is not overdone. The mask (selection) is then removed using the shortcut Ctrl D.
A reversed gradient was also created from the bottom up to the top and the resulting mask used to darken the lower regions of the door. Note in the second image that the mask border isn’t showing. Here I used Ctrl H to hide the border so I could see the adjustment without that distraction.
At this stage the door is looking pretty good but a few other adjustments can be made. I like to increase the contrast (Image/Adjustments/Brightness/Contrast…) on inworld textures a little when I am using photographs. This tends to help the textured object “pop” out from the scene a little and not look too washed out in the inworld lighting.
Further adjustments can also be made in terms of the lighter and darker areas of the image. Rather than affect the whole image using gradient masks and levels as shown above, now I use the Dodge and Burn Tools to touch up specific areas. The Dodge Tool is used to lighten an area and the Burn Tool to darken it. It is essential here to set a soft edge to the brush when applying these effects so harsh edges aren’t created on the image.
Finally a little sharpening is again applied to the image to clean up any fuzziness created by the light adjustments.
Completing the Image Resize
All that remains to do now is to resize the width of the image to conform to the power of two requirement. As the image is currently 226 pixels wide the nearest power of two is 256 pixels. In resizing this time I want the height to remain at 512 pixels so I deselect Constrain Proportions and then enter the width value as 256.
The image is now ready to be saved as a texture, my preference being to save as a .tga file though BMP, JPG and PNG formats are also supported. For quality and compatibility the bit depth should be at least 24-bit colour. When you upload a texture Second Life converts (and compresses) it to the JPEG2000 format so to ensure better quality, already compressed JPG formats should really be avoided.
This concludes the two posts on creating a non-tileable texture for use in Second Life or OpenSim.