Saturday, November 4, 2017
1) Contrast and Gamma, (levels),
can be adjusted to fix "washed-out" appearance of photo.
If your camera messes up the white-balance, this can also be corrected "post-process" in Photo Shop w/ Set White Balance eyedropper in LEVELS to "sample" lightest part of background in photo. (And correct the WB based on color temperature of BG "sample").
This is assuming all photo lighting is of same type, (Sunlight, incandescent, all same brand / type of fluorescents, et. al).
Finding right EV compensation is subject to experimentation... (+1 might be too much, or not enough, to compensate for white BG's).
2) Low camera ISO setting, (and MORE lighting), is better than high ISO, (and less lighting), because higher ISO's suffer from increasing "graininess" / "noise" than a lower ISO setting does.
3) "Selecting" out subject / object from BG can also be done w/ Lasso / Free-Select tool, (instead of Paths tool); the important part is that subject-selection is Inverted so that BG can be filled-in w/ contrasting color, (BG fill is created as separate layer above main photo layer, so that mistakes in BG fill can be easily fixed w/out starting all over again...).
Specific Instructions For GIMP Original Image of object: (Note yellowish BG and low contrast).
(Image to come)
Color and Contrast-corrected photo using Set White-Point eyedropper in Levels to "sample" lightest area of yellowed BG.
Set Black Point adjustment-slider to 19 and Gamma adjustment-slider to 0.95 to improve image contrast:
(Image to come)
Same color-corrected, contrast-enhanced photo with addition of Overlay Mode white background-fill layer, set to 88.8% opacity to still reveal some shadow detail.
(Created by tracing calc outline w/ lasso select tool, inverting selection, feathering selection 7 pixels, creating new transparent layer, filling selection area w/ white, and finally, setting Layer Mode to Overlay and Layer Opacity to 88.8%).
(Image to come)
Furthur Instructions Levels dialog, specific Set Black Point, Set Mid-Point slider-adjustments (Gamma), and Set White Point Eyedropper all circled in highlighter.
Like the fact that image histogram graph is displayed in Levels dialog: (Makes setting Black Point level very intuitive...).
(Image to Come)
Another screen-cap showing layers of photo-editing: (Only layers made visible, indicated by Eye symbol, appear in final JPG image-export).
3) Color-corrected and Levels-adjusted image layer.
2) White background fill-layer 1, created by selecting calculator using Lasso-select tool, feathering selection-edges, inverting selection, creating new, transparent layer and filling still-active selection-area w/ pure white, (255 units of Red, Green and Blue).
This layer is set to Saturation mode, (at 100% opacity), to remove remaining discoloration. (Does not affect shadows nor brightness of BG fill, however).
1) Topmost background fill-layer, (duplicate of BG fill layer 1), set to Overlay mode and 80% opacity to brighten BG yet leave a small amount of shadow-detail.