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No longer try to adjust exposure once limit is hit, make prints go to…
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… log file, put config parameters in a struct
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@Matthias-Wandel
Matthias-Wandel committed Dec 2, 2020
1 parent c6b0c38 commit 2c8832e
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Showing 3 changed files with 84 additions and 61 deletions.
5 changes: 3 additions & 2 deletions src/compare.c
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Original file line number Diff line number Diff line change
Expand Up @@ -49,8 +49,9 @@ TriggerInfo_t ComparePix(MemImage_t * pic1, MemImage_t * pic2,

if (pic1->width != pic2->width || pic1->height != pic2->height
|| pic1->components != pic2->components){
fprintf(stderr, "pic size mismatch! %dx%d vs %dx%d\n",pic1->width, pic1->height, pic2->width, pic2->height);
return RetVal;
fprintf(stderr, "pic size mismatch (maybe clear ramdisk?)\n %dx%d vs %dx%d\n",pic1->width, pic1->height, pic2->width, pic2->height);
exit(-1);
//return RetVal;
}
width = pic1->width;
height = pic1->height;
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138 changes: 80 additions & 58 deletions src/exposure.c
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Original file line number Diff line number Diff line change
Expand Up @@ -15,16 +15,28 @@

static double ISOtimesExp = 5; // Inverse measure of available light level.

static double ISOoverExTime = 4000; // Configured ISO & exposure time relationship.

static int ISOmin = 0, ISOmax = 0;
typedef struct {
int ISOmin, ISOmax; // ISO limits for camera module.
float Tmin, Tmax; // Exposure time limits.

int SatVal; // Saturated pixel value (some cameras saturate before 255)
int ISOoverExTime; // Target ISO/exposure time. Larger values prioritize
// fast shutter speed at expenso of grainy photos.
}exconfig_t;

exconfig_t ex;

static int ExMaxLimitHit = 0; // Already at maximum allowed exposure (ISO and exposure time maxed)
static int ExMinLimitHit = 0; // Already at minimum allowed exposure (ISO and exposure time minimized)

//----------------------------------------------------------------------------------------
// Compute shutter speed and ISO values and argument string to pass to raspistill.
//----------------------------------------------------------------------------------------
char * GetRaspistillExpParms()
{
// if ISO min/max are not configured manually, set the according to camera module.
if (ISOmin == 0 || ISOmax == 0){
if (ex.ISOmin == 0 || ex.ISOmax == 0){
int min, max;
if (memcmp(ImageInfo.CameraModel, "RP_ov5647",10) == 0){
//V1 (5 mp) camera module
Expand All @@ -38,31 +50,44 @@ char * GetRaspistillExpParms()
// HQ (12 mp) camera module.
min = 40; max = 1250;
}
if (ISOmin == 0) ISOmin = min;
if (ISOmax == 0) ISOmax = max;
if (ex.ISOmin == 0) ex.ISOmin = min;
if (ex.ISOmax == 0) ex.ISOmax = max;
}
// Set Tmin and max if not configured.
if (ex.Tmin <= 0.0001) ex.Tmin = 0.0001;
if (ex.Tmax == 0) ex.Tmax = 0.1;
if (ex.Tmax <= 0.001) ex.Tmax = 0.001;
if (ex.ISOoverExTime < 100) ex.ISOoverExTime = 4000;


double ExTime = 1/sqrt(ISOoverExTime/ISOtimesExp);

if (ExTime < 0.001) ExTime = 0.001;
if (ExTime > 0.5) ExTime = 0.5;
double ExTime = 1/sqrt(ex.ISOoverExTime/ISOtimesExp);

if (ExTime < ex.Tmin) ExTime = ex.Tmin;
if (ExTime > ex.Tmax) ExTime = ex.Tmax;
double ISO = ISOtimesExp / ExTime;

// Apply limits to ISO.
if (ISO > ISOmax) ISO = ISOmax;
if (ISO < ISOmin) ISO = ISOmin;
if (ISO > ex.ISOmax) ISO = ex.ISOmax;
if (ISO < ex.ISOmin) ISO = ex.ISOmin;

// Re-compute exposure time, in case we hit ISO rails.
ExTime = ISOtimesExp / ISO;

// Re-apply limits to exposure time.
if (ExTime < 0.001) ExTime = 0.001;
if (ExTime > 0.5) ExTime = 0.5;


ExMaxLimitHit = ExMinLimitHit = 0;
if (ExTime < ex.Tmin) {
ExTime = ex.Tmin;
ExMinLimitHit = 1;// too much light. Kind of unlikely.
fprintf(Log,"Exposure at min ISO and time.\n");
}
if (ExTime > ex.Tmax) {
ExTime = ex.Tmax;
ExMaxLimitHit = 1;// Dark image, but further exposure increase not possible.
fprintf(Log,"Exposure at max ISO and time\n");
}

printf("New t=%5.3f ISO=%d",ExTime, (int)ISO);
printf(" ISO*Exp=%4.0f\n",ISOtimesExp);
fprintf(Log,"New t=%5.3f ISO=%d ISO*Exp=%4.0f\n",ExTime, (int)ISO,ISOtimesExp);

static char RaspiParms[50];
snprintf(RaspiParms, 50, " -ss %d -ISO %d",(int)(ExTime*1000000), (int)ISO);
Expand All @@ -80,11 +105,9 @@ int CalcExposureAdjust(MemImage_t * pic)
if (Region.y2 > pic->height) Region.y2 = pic->height;
if (Region.x2 > pic->width) Region.x2 = pic->width;


int BrHistogram[256] = {0}; // Brightness histogram, for red green and blue channels.
int NumPix = 0;


int rowbytes = pic->width*3;
for (int row=Region.y1;row<Region.y2;row++){
unsigned char *p1;
Expand All @@ -110,12 +133,12 @@ int CalcExposureAdjust(MemImage_t * pic)
int twobin = BrHistogram[a]+BrHistogram[a+1];
if (twobin > maxv) maxv = twobin;
}
printf("Histogram. maxv = %d\n",maxv);
fprintf(Log,"Histogram. maxv = %d\n",maxv);
for (int a=0;a<256;a+=2){
int twobin = BrHistogram[a]+BrHistogram[a+1];
printf("%3d %6d %6d ",a,BrHistogram[a], BrHistogram[a+1]);
fprintf(Log,"%3d %6d %6d ",a,BrHistogram[a], BrHistogram[a+1]);
static char * Bargraph = "#########################################################################";
printf("%.*s\n", (50*twobin+maxv/2)/maxv, Bargraph);
fprintf(Log,"%.*s\n", (50*twobin+maxv/2)/maxv, Bargraph);
}
}

Expand All @@ -125,6 +148,7 @@ int CalcExposureAdjust(MemImage_t * pic)
int satpix = NumPix / 32; // Allowable pixels near saturation
int medpix = NumPix / 4; // Don't make the image overall too bright.
int sat, med;
int SatVal;
for (sat=255;sat>=0;sat--){
satpix -= BrHistogram[sat];
if (satpix <= 0) break;
Expand All @@ -135,59 +159,58 @@ int CalcExposureAdjust(MemImage_t * pic)
}
double SatFrac;
{
int SatPix = 0;
int sat = 253;
if (memcmp(ImageInfo.CameraModel, "RP_ov5647",10) == 0){
// 5 megapixel module saturates around pixel value of 245, not 255.
// Newer modules pixel values saturate closer to 255
sat = 244;
if (ex.SatVal){
SatVal = ex.SatVal;
}else{
SatVal = 253;
if (memcmp(ImageInfo.CameraModel, "RP_ov5647",10) == 0){
// 5 megapixel module saturates around pixel value of 245, not 255.
// Newer modules pixel values saturate closer to 255
SatVal = 244;
}
}
for (;sat<256;sat++){
SatPix += BrHistogram[sat];
int SatPix = 0;
for (int a=SatVal;a<256;a++){
SatPix += BrHistogram[a];
}
SatFrac = (double)SatPix/NumPix;
}

printf("Brightness: >3%%:%d >25%%:%d Sat%%=%3.1f\n",sat,med, SatFrac*100);
if (sat < 220){
// Adjust exposure upwards becauase very few pixels are near
// maximum values, so there's exposure headroom.
double Mult=10,Mult2=10;
if (sat) Mult = 230.0/sat;
if (med) Mult2 = 210.0/med;
if (Mult2 < Mult) Mult = Mult2;
if (Mult > 32) Mult = 32; // Do't try to adjust more than this!

ExposureMult = Mult;
}else{
// Adjsut exposure downward because too many pixels
// have saturated. It's impossible to calculate how far down
// we really need to adjust cause it's saturating, so just guess.
if (SatFrac > 0.03) ExposureMult = 0.8;
if (SatFrac > 0.06) ExposureMult = 0.7;
if (SatFrac > 0.12) ExposureMult = 0.6;
if (SatFrac > 0.20) ExposureMult = 0.5;
if (SatFrac > 0.40) ExposureMult = 0.4;
}
// Adjust exposure upwards becauase very few pixels are near
// maximum values, so there's exposure headroom.
double Mult=10,Mult2=10;
if (sat) Mult = 0.9*SatVal/sat;
if (med) Mult2 = 0.82*SatVal/med;
if (Mult2 < Mult) Mult = Mult2;
if (Mult > 32) Mult = 32; // Do't try to adjust more than this!
ExposureMult = Mult;

// Adjsut exposure downward because too many pixels
// have saturated. It's impossible to calculate how far down
// we really need to adjust cause it's saturating, so just guess.
if (SatFrac > 0.03) ExposureMult = 0.8;
if (SatFrac > 0.06) ExposureMult = 0.7;
if (SatFrac > 0.12) ExposureMult = 0.6;
if (SatFrac > 0.20) ExposureMult = 0.5;
if (SatFrac > 0.40) ExposureMult = 0.4;

double LightMult = pow(ExposureMult, 2.2); // Adjust for assumed camera gamma of 2.2

// LightMult indicates how much more the light should have been,
// or how much to multiply exposure time or ISO or combination of both by.
printf("Pix mult: %4.2f f-stop adjust: %5.2f\n",ExposureMult, log(LightMult)/log(2));
fprintf(Log, "Brightness: >3%%:%d >25%%:%d Sat%%=%3.1f Ex adjust %4.2f\n",sat,med, SatFrac*100, LightMult);

double ImgIsoTimesExp = ImageInfo.ExposureTime * ImageInfo.ISOequivalent;

ISOtimesExp = ImgIsoTimesExp;

if (LightMult >= 1.25 || LightMult <= 0.8){
if ((LightMult >= 1.25 && ExMaxLimitHit == 0)
|| (LightMult <= 0.8 && ExMinLimitHit == 0)){
// If adjustment is called for, *and* we aren't at the limit.
printf("Adjust exposure. Was: t=%6.4fs",ImageInfo.ExposureTime);
printf(" ISO=%d ISO*Exp=%f\n",ImageInfo.ISOequivalent, ImgIsoTimesExp);

ISOtimesExp *= LightMult;
ISOtimesExp = ImgIsoTimesExp * LightMult;
GetRaspistillExpParms();
return 1; // And cause raspistill restart.
// And cause raspistill restart.
return 1; // And signal raspistill needs restarting.
}
return 0;
}
Expand All @@ -196,7 +219,6 @@ int CalcExposureAdjust(MemImage_t * pic)

// Todo next:
// Use weight map for exposure calculation
// Limits to ISO range and shutter speed?
// Make more parameters configurable
// Make exposure stuff print less (maybe print brightness once a minute unless it changed)

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2 changes: 1 addition & 1 deletion src/start_raspistill.c
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Original file line number Diff line number Diff line change
Expand Up @@ -116,7 +116,7 @@ int relaunch_raspistill(void)
int l = strlen(cmd_appended);
sprintf(cmd_appended+l," -o %s/out%c%%05d.jpg",DoDirName, OutNameSeq++);
if (OutNameSeq >= 'z') OutNameSeq = 'a';
printf("Run program: %s\n",cmd_appended);
//fprintf(Log,"Run program: %s\n",cmd_appended);
}

pid = fork();
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