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experiment 

Now scaling pixels to 255 levels looks a lot better. Still worse,
though. On both t.pgm and barbara.pgm.
This commit is contained in:
Kartik K. Agaram 2021-07-13 13:22:01 -07:00
parent 1004372711
commit b4e997adb8
1 changed files with 19 additions and 7 deletions
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26
img.mu
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@ -27,16 +27,15 @@ fn main screen: (addr screen), keyboard: (addr keyboard), data-disk: (addr disk)
var img-storage: image
var img/esi: (addr image) <- address img-storage
load-image img, data-disk
render-image screen, img, 0/x, 0xd0/y, 0x12c/width=300, 0xc8/height=200
render-pgm-image screen, img, 0x140/x, 0/y, 0x12c/width=300, 0xc8/height=200
render-image screen, img, 0/x 0/y, 0x400/width 0x400/height
}
fn load-image self: (addr image), data-disk: (addr disk) {
# data-disk -> stream
var s-storage: (stream byte 0x200000) # 512* 0x1000 sectors
var s/ebx: (addr stream byte) <- address s-storage
#? draw-text-wrapping-right-then-down-from-cursor-over-full-screen 0/screen, "loading sectors from data disk", 3/fg, 0/bg
#? move-cursor-to-left-margin-of-next-line 0/screen
draw-text-wrapping-right-then-down-from-cursor-over-full-screen 0/screen, "loading sectors from data disk", 3/fg, 0/bg
move-cursor-to-left-margin-of-next-line 0/screen
load-sectors data-disk, 0/lba, 0x100/sectors, s
load-sectors data-disk, 0x100/lba, 0x100/sectors, s
load-sectors data-disk, 0x200/lba, 0x100/sectors, s
@ -53,8 +52,8 @@ fn load-image self: (addr image), data-disk: (addr disk) {
load-sectors data-disk, 0xd00/lba, 0x100/sectors, s
load-sectors data-disk, 0xe00/lba, 0x100/sectors, s
load-sectors data-disk, 0xf00/lba, 0x100/sectors, s
#? draw-text-wrapping-right-then-down-from-cursor-over-full-screen 0/screen, "parsing", 3/fg, 0/bg
#? move-cursor-to-left-margin-of-next-line 0/screen
draw-text-wrapping-right-then-down-from-cursor-over-full-screen 0/screen, "parsing", 3/fg, 0/bg
move-cursor-to-left-margin-of-next-line 0/screen
initialize-image self, s
}
@ -453,6 +452,12 @@ fn dither-pgm-unordered _src: (addr image), _dest: (addr image) {
var dest-height-a/ecx: (addr int) <- get dest, height
copy-to *dest-height-a, tmp
}
# compute scaling factor 255/max
var target-scale/eax: int <- copy 0xff
var scale-f/xmm7: float <- convert target-scale
var src-max-a/eax: (addr int) <- get src, max
var tmp-f/xmm0: float <- convert *src-max-a
scale-f <- divide tmp-f
# transform 'data'
var capacity/ebx: int <- copy src-width
capacity <- multiply src-height
@ -484,6 +489,13 @@ fn dither-pgm-unordered _src: (addr image), _dest: (addr image) {
#? var foo/eax: int <- copy initial-color
#? psd "r", foo, 7/fg, x, y
#? }
# . scale to 255 levels
var initial-color-int/eax: int <- copy initial-color
var initial-color-f/xmm0: float <- convert initial-color-int
initial-color-f <- multiply scale-f
initial-color-int <- convert initial-color-f
#? var initial-color/eax: byte <- copy-byte initial-color-int
#
var error/esi: int <- _read-dithering-error errors, x, y, src-width
#? {
#? var foo/eax: int <- copy error
@ -504,7 +516,7 @@ fn dither-pgm-unordered _src: (addr image), _dest: (addr image) {
#? }
# error += (initial-color << 16)
{
var tmp/eax: int <- copy initial-color
var tmp/eax: int <- copy initial-color-int
tmp <- shift-left 0x10 # we have 32 bits; we'll use 16 bits for the fraction and leave 8 for unanticipated overflow
error <- add tmp
}